Now that I think of, I take back my vote on 100 cap.
My thoughts...
Since Im pretty sure you won't give free silk I won't be playing on this server anyway. Too much damn greedy servers these days. All they want is money.
And they make everything nice that silkroad has to offer for money, f*** them.
It was okay to play in global with no silk since you could buy silk items for gold but in private servers a donator is rare thing so pretty much no silk items available for gold and even if it is the price is f-ing crazy.
Now about some of your ideas.
Don't give that much of free sp, everything in silkroad is for purpose, to keep player busy and when you take that away player will leave sooner or later because he will get bored faster. To make it easier give 250k or a million sp, but dont make instant full farm.
About starting items, 3 day pet? Seriously? Thats like starting with nothing.
Why do all private server owners imagine getting profit from their server instantly? It doesn't happen that way. Give players one premium, a full pet and ds, after a month when they end them they might donate because they enjoyed server, see potential and future, not some greed (ofcourse you need to make those starting items not tradable so there wouldnt be abuse of them).
Managing silkroad server is a business and when you create a new business in real world you don't expect getting instantly rich, do you? You make huge discounts, give free stuff and so on to attract people and when you have big enough fan base you can start earning money.
Anyway If you make a server like I have read you will have like 100, maybe max 200-300 people after few months, you won't be that much popular, I can garantuee that. And also looking at your past failures (like 20 servers) I don't expect this one to last long enough to be profitable at all, expecially with your managment.
Also cap doesn't really matter that much, 110 cap might be even better than 90 or 100 because of job cave, more uniques, coins for egypt items and fgw. I have huge silkroad experience, have played in lots of 90, 100 and 110 cap servers and I can say that all caps are pretty much balanced in their own way. Since you won't give free silk 100 cap can be pain in the a** with its ridiculous jangan cave, even with teleporters to B-x places and its kinda boring, only interesting stuff in 100 cap is medusa which gets boring really fast if you are not wizard. Any cap below 100 in my own opinion is just stupid since china gets its useful skills only in and after 100 cap.
P.s. all most populated private servers are 110 cap so making anything than 110 is risky.