Quick clarification:
When you say "customize your mech", you mean customize it pre-campaign, correct?
Yes. Once the campaign starts, you can customize freely and min-max to your black little hearts' content. It just means that the computer-generated OPFOR will have a higher BV to build the OPFOR against. Likewise, the computer randomly assigns (IIRC) somewhere between 40 and 80% of the SPA's you have available in each mission, so if the deployed PC unit has 20 SPAs between them, the computer will assign somewhere between 8 and 16 SPAs to OPFOR pilots.
Oh, and of course you'll have to use the normal customization rules, which means your customization will generally take 10,000-20,000 minutes of work, the Tech assigned to it can't do anything else while doing the customization work, and you make a skill roll at the END of the customization and if you fail, the customization doesn't work and the time (though not components) is completely lost. If you pass with exactly the TN required, you gain Quirks. If you pass the TN, then the customization works. Customization TNs for a regular Tech are (IIRC) roughly a 9+, down to a ~6+ for an Elite Tech. Customizations should not be treated as a given nor entered into lightly.
Regarding your questions:
1) Nope. Because it'll be based on which contract you choose. You're starting on Outreach because it's easy and central, and then if you select a contract in the MoC, then you'll just have to travel out that far. If you select a contract on New Earth, then you'll have like a 2-week trip.
2) See StratOps
3) Generally speaking from each contract, the unit will receive 5 shares, and each person will receive 1 share for their personal upkeep. If there's a 10 million CB payment at the end of the contract, and there's 5 PC lances, then each lance will get 1 milllion CB and the unit will get 5 million CB. If you want something too expensive for you personally to buy, you can ask the unit to subsidize you. And since you brought it up, salvage goes to the unit and players can ask it be given to them for repair/refit. If a unit doesn't get assigned to a lance after 6 months, or the whole unit agrees, or you don't have space on the DropShip to carry it, then it'll get sold for CB and the cost split as usual.
4) It's part of force creation and I can't do it until everyone is done with thier forces.
5) Depends on the customizing. Again, your techs are completely responsible for doing all maintenance, repairs, and customizations for your own lance. If you are on a planet like Outreach, then you're still responsible for it, but you'll qualify as automatically having access to a Factory facility (approx. -4 to Repair TNs), because there's Mech factories on that planet. If you're on a planet without a factory, and you have a DropShip, and you're assigned to Defense or Fight status, a DropShip counts as a maintenance facility (approx. -2 to Repair TNs). And no, you may not sub-contract tech support, because allowing that defeats the entire purpose of having you each run a mini merc unit on your own. Again, each lance will be guaranteed to have a couple Techs (IIRC, 1 Vet, 1 Reg) at the end of force creation; if the force doesn't get enough of those to start out with, the number of Techs will be increased to ensure that happens. Beyond that, if you want a better/more Techs, go hire them. Each month you're on-planet you'll get a list of people who are available for hire, their skill rating, their salary, their hiring bonus, and the minimum contract you're signing them up for before they qualify for retirement rolls (usually 1-5 years).
Side note: as far as I can determine, if you're actually repairing a Mech, the basic maintenance time is automatically done during the repair. StratOps maintenance occurs EVERY TIME a Mech is deployed or used in a game (unless it's been errata'd, which I should probably go look at).