That's something I've done slight research, designing a full-unique script would be expensive, The coders and graphics would require at least 3-4 thousands if it's of good quality (and that's from cheaper coders and designers, for something new - with few unique games, and importing the rest from game providers, Domain can be very cheap or very expensive (for example stake, which is VERY expensive).
Hosting isn't a big fee, advertising would be the most expensive possibly for several BTC's, considering how saturated the market is, there is a need for something to attract new players.

Unlikely IMO, Gambling might be profitable on short term on 4-5 dice rolls or the like, but on long term it's not like that, since the negative odds of winning known as the casino house edge accumulate, giving a user a negative profit over the long term.

Obviously that's a very integral part of it and of it's nature, The majority of people are still here because of that and that's why casino's and sportbooks offer VERY favorable options for your first bets, trying to get you in the wagon.

I am shocked with the 0% for American FB, it's my favorite and the odds of winning or getting better terms then it's definitely football, both NFL and College football,
Tennis and Basketball are also good and better IMO specially more than Soccer, which has the third outcome of draw.

Depends on the exact definition of money, I would say it is since it's exchangeable with value toward items, although the value isn't stable and fluctuate depending on the market and other factors as well, but in the end, it has an intrinsic value without even exchanging it and can be used directly to buy some items, hence money.

To actually make a new client, you would need allot of money for developing as well as securing it, and time to get the trust of users. if it's an online wallet then it would be even more, considering the bad reputation of online wallets and storages with the exception of 1-2 wallets that avoided the risk of exploits and hacking.

Even in the best case scenario and BTC hitting unrealistically high values like $100,00,00, Having something like 0.10 or 0.01 BTC can't be called a bad thing, since you would get something from the cake HOWEVER if getting a full bitcoin at one time would be possible, that would be a reason of regret of not buying it, in this scenario case, even though a fraction does work, it would still mean you are not heavily investing into this market.