.. wondering whats the best site to play with this balance.. or do i just need to add more to it just to be safe?
There is no best sites for this purpose because gambling is gambling, no matter where you play then luck will be only the key to help you. Just make sure that you are going to play in a provably fair gambling site and trusted one and let your luck decide what is the best for you.

Add more balance wont give you more safety, just play with the money that you can afford to lose (as mentioned/suggested many times already). Dont force yourself bet more than what you can afford to lose.
The house edge on certain online casinos is different, and odds for certain games may differ from site to site, but in general what you've mentioned is correct.
Due to the house edge on every casino, you're never going to win in the long run (which is something you should already know). If you enjoy gambling, set aside a certain amount of money every week or month to gamble as a control mechanism. If you want to make money, investing in a casino
can be profitable, but not always. Lending to an exchange may also be a good idea.
Every casino or gambling do have a specific house edge but they are just almost identical to each other and as you said due to house edge this will really be a big factor why we cant able to sustain on winning on playing gambling.Money allocation on weekly basis is a good step or good control to yourself that those money are just really lend to play gambling and theres no other than that but sometimes or most people do failed up to have such behavior. 100k sat balance can give you some enjoyment but dont think that you can make money out of it.If youre lucky then you might gain some but having that kind of balance wont really give too much returns when you won.