You don't put lot size in your signal settings, but the participation percentage with max 95%.
The lot size is calculated automatically based on your balance, currency and leverage.
With the above balances and same leverage, your copying ratio will be about 160%, so when the signal opens 0.03 lots, you will open 0.04 (and not 0.05).
You can see example calculations in this article.https://www.mql5.com/en/articles/618
The lot size is based on your copying ratio, that is calculated automatically by MQL5 signal copying system.
You can find this copying ratio in your MT4/5 or MQL5 VPS journal.
Yes, but you will need to pay on the same way as on real account.