Regarding the slight out of balance in terms of USD is not a problem at all in my opinion with all those suggested pairs.
I think stick with what has been working, and experiment with small changes at a time rather than a large overhaul.
Yes 10 different strategies on EURUSD can be a balanced portfolio. I would prefer they were spread over different periods though. 2-3 for M15, M30,H1 and H4 would be better.
Yeah I’d think once you have enough on EURUSD move to different pairs. 1000 is more than enough in your pool for any single pair and timeframe though.