You can do this on small accounts (5k Usd) - just make sure you run with 200:1 leverage, minimum trade size 0.01 lot. And regarding your second question (I generally build systems that add to winners - so I run 10 per account max)
I am in this Situation, i have ~ 300 run on Demo, from this after ~ 2-3 Months, the best 100 take and make ob Account with Leverage 1:400 and 0.01 lot
Every week i check with very nice Tool from Sleytus and i can see now after new 2-3 Months, from this ~ 3-5 good EA
This EA i would now check with 0.02 Lot.
I run every Day EAStudio with strong settings to find 100 EA in each Pair and make the same .... Demo....live..0.01....
I run for this EAStudio min. 7.200 Minutes.
I very gladly when i have after 1 year ~ 10 very good EA