Clothes for Mike mostly give a small bonus to strength, charm, or intelligence if you wear them. Some clothing is also needed to access certain locations, namely fancy suit, swimsuit, and sport clothes. Clothes for girls are mostly LP raisers, however sexy dress, sexy swimsuit, and slutty dress will also change the look of some characters in certain locations.
A list of items is
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With the skills, you have two new ones I haven't tried yet, maybe somebody else can help. Workaholic is a trait that speeds up work progress and time for salary raises. Most traits only have minor influence on gameplay however. There may be specific scenes where you get a bonus, or you may have 1 LP more when meeting a girl.
If you want to start anew after some playtime I would suggest picking Martial Arts in the first conversation/question with Bree, it is the only trait that you really need. And while you can learn it in game, it may be a race with time and it is quite specific to get (only on the beach, so only during summer, which is crowded with events anyway, and you'll need at least a bike).
Sexperience shouldn't be an issue. Granted, in real life after 144 times you should be able to distinguish the holes, but Mike can be daft sometimes.