Tony - this looks like you have a very good strategy here - congratulations.
You have have done some very mindful back-testing and forward testing, with a good sample size and all looks well. Your results are impressive.
To answer your qusetions - here are my humble opinions on your questions (and I do concur with most of the other advice on your thread)
- It does appear to be viable - it works, it is your system to make your own - well done do not stray from your rules.
- Yes, it can get you through a prop firm challenge. be mind full of the prop firm you choose and that they are reputable and their rules suit you.
- NOW THIS IS IMPORTANT - and the main reason people fail prop challenges.
Lets imagine that you take a $100,000 challenge and your maximum drawdown is $10,000. - $10,000 is really your account Not $100,000. You will have the margin/leverage of a $100,000 account but in reality your account is your drawdown.
So think in terms of the percentage risk of that $10,000. This is upto you to decide - your risk tolerance and safe tolerance. Many traders risk 1% -2% BUT that must be of $10,000 (your drawdown) not the $100,000. Prop firms do not usually explain this!
I am not a set TP trader - I do not have a crystal ball - Let your winners run, unless of course, you can’t be there and you have to set and forget. You didn’t mention your preferred time frame, 15 trades a day suggests you use lower timeframes, not that it matters, if you if you use higher timeframes you may have to set and forget. Anyway, your strategy seems to work well - why change it?
Having said that - the only thing we can control is our risk STOP LOSS
All the best with what l looks a good strategy. 
Stay cool 