I didn't read the above post as I'm quite busy, but in reading your question, I can try give some pointers regarding the o-chem section. I apologize in advance for the length, but I'd like to address all your points as best I can. Firstly, on my exam, the o-chem was quite basic and comprised very little of the section. There was some basic nomenclature, but not a ridiculous amount. There was one question that I'm sure tricked a lot of people. It was a bromination question and at first glance, I almost missed that two of the alkenes in question were different pre-reaction but actually yielded one product in common after bromination. I'd take a look at those kinds of situations (there's also a very simple variation on the SN2 reaction called SN2' that may be worth a quick glance). Simply put, it occurs when you have an allylic halide that gets attacked at the carbon farthest from the halide such that the double bond moves and displaces the halogen. As a simple example:
CH2=CH-CH2-Br + Nu- ---> Nu-CH2-CH=CH2 + Br-
If you can't make sense of that, review your substitution reactions. And as always, recognize that elimination is almost always in competition with substitution and is favored by heating the mixture.
For your other questions, knowing stereochemistry is absolutely a must. I had a question that just gave the name of the reactant and its configuration, told you what it was treated with, and had you pick the name of the product. It was kind of tricky because it was clear it was an SN2 reaction, so instinctively I almost chose the answer that simply had inverted stereochemistry, but remember, inversion of stereochemistry doesn't necessarily mean inversion of absolute configuration (R-> S or S-> R). It depends on the nucleophile and the nature of the other substituents! Take the extra time to draw the reactant and product and actually assign configurations based on the CIP rules. In my case, it was S and stayed S, despite being SN2.
I don't recall too much about fatty acids, but it's good to understand their amphiphilicity and how it can be exploited in various ways (all that comes to mind is acid/base extraction, but the solvents would have to be chosen carefully). DEFINITELY know carbonyl chemistry. There will almost certainly be a question whose sole purpose is to test your understanding of leaving groups and know when carboxylic acid derivatives can be converted (i.e. acyl halide to ester). Also remember that when you throw a carbonyl compound into acid, the carbonyl oxygen generally gets protonated before anything else, and it's this formal positive charge that makes the carbonyl carbon more electrophilic to the conjugate base of whatever acid was used.
Carbohydrate chemistry was basic. Know how to assign configuration based on Fisher projections and whether a ring carbohydrate is alpha or beta. Proteins you don't need to know too much except their general structure. Don't worry about the structures of each amino acid (but it might be wise to recognize that glycine is the only achiral AA). They may give you a peptide chain and ask how many distinct AA's are present, which just requires that you know the general NH2-CHR-COOH structure and be able to see the subunits. This is analogous to being given a polymer and determining the subunit that made it or, alternatively, being given a subunit and being asked what polymer it would create (review radical polymerization).
Know general bonding theory (hybridization) and what geometries different molecules adopt (remember, electronic and molecular geometries are not always the same!). Isomerism is pretty straightforward. I don't think they'd throw a carbocation rearrangement question at you, but you'd do well to be able to spot them. Reactions of hydrocarbons is important but may or may not be tested. Just be familiar with alkene, alkyne, and alkane reactions, including combustion reactions (contrary to popular belief, CO2 and H2O are not the only products of combustion and water sometimes isn't a product at all. Remember all you're introducing is O2, so the products can only contain elements present in the combusted material. I had a question about this in which hydrogen was absent, hence H2O not being a product).
Finally, I think o-chem lab could be beneficial, but understanding the techniques is far more beneficial. For example, if you're given a mixture of 3 components (structures given) and are told the protocol used to separate them, would you be able to logically deduce which compound is removed at which step and why? It generally amounts to hydrophobicity/hydrophilicity or acid/base extraction. Recrystallization may also appear, but generally just looking at a PC table is sufficient. The key idea is that you want a solvent that solvates the solute to significantly different extents with changing temperatures. Something soluble in both cold and hot water, for example, will not recrystallize. Another lab concept that may be tested is boiling points, but again, these will likely be given in a PC table. Questions to ask yourself, should/can I use simple distillation to separate these? Do the substances decompose at a certain temperature? etc.
I think I covered most of your points the best I could, but feel free to ask any further questions. If you're taking an actual prep course, I wouldn't burden yourself with o-chem as well unless you really don't feel comfortable with it. I took 21 credits the semester I took the MCAT and only had spring break to study. I pulled it off, but it was stressful. If you can avoid unnecessary pressure, do it. Hope this helps some, and good luck!
