While it's not his primary profession, my primary character has loaned large sums of money and extended serious amounts of credit before (more often it's "this magic item or ritual scroll for X gold to be repaid over Y period of time" than pure coin, for reference). Here's my take on your list:
1. Yep, big capital is an important issue. This will scale with your level, though, and quickly jumps up esp. if you go all craftsman other with a MWE.
2. PCs who play generally gave no problems with repayment terms. I doubt you would have any issues hiring *other* PCs to help deal with "problem debtors", either.
3. This is definitely an issue. Most players simply don't have a need for a bunch of coin. I find that you are far more likely to make money by investing yourself in items/scrolls/production items whenever you get a chance, and expect to sell/loan those items instead of pure coin. The opportunity to spend a big chunk of gold just doesn't come up often enough to make a pure moneylender viable, at least not in my experience.
4. This is the biggest issue I've run into. Big loans take OOG years to repay, so you need to be in it for the long haul. My (unfortunate) experience is that out of 10 loans / batches of credit that I give, 4 or 5 will never get fully repaid due to the character retiring/quitting before the end of the loan. You will want to seriously consider your credit risks well, because you have no method of enforcement for a player who simply stops playing that character, unlike the real world. Also, make sure you have a good OOG feel for the average lifespan of a character in your chapter - not to permanent death, but to simply stopping being played.
5. Craftsman:Other x 200 for a MWE is a pretty solid start. 20 gold a day before doing *anything* is incredible income. You will however want to think OOG of what this means for your chapter. That's a really hard thing for them to have to support, simply because your character will be sucking up a *lot* of OOG resources in the form of hard coinage.
Hope these thoughts help!
-Bryan