Mr.fixit

You can't avoid going down yourself eventually eg. opening bank accounts, selection of scooter/car, etc. Nobody is going to do it free for you unless you pay (tell me if you need & I can recommend some friends), so it is best to still do it yourself. I can give you some ideas if you are new to Phnom Penh:

Banks: You might consider going to foreign banks that are normally "foreigner-friendly", ie. speaking reasonable level of English. You can try ANZ (but they have a minimum sum to maintain otherwise a bank charge applies), Cambodian Public Bank (for their extensive branches and interest-bearing current accounts), CIMB, Maybank, etc.

Visas: most travel agencies will be able to handle them. You can find plenty of them along the riverside.

Insurance: Cambodian Public Bank has an insurance arm at their main branch

Scooter / car: depends on what you need, new/second-hand and your budget.