What do you folks recommend? I am based in Slovakia, Europe if it matters.
With $5k bankroll your only reasonable choice is to find good ECN broker locally or anywhere in EU.
People in US don't understand that there are plenty of ECNs brokers in EU, that while they carry "forex" in their name, they have little to do with how forex brokers used to (some still) work.
The main advantage is that for currencies not only you get much tighter spreads than CME, but more importantly you can buy mini (0.1) and micro (0.01) lots (or any size you wish) and your commissions are paid based on the size traded. So if your size is 0.54 of one lot, you pay 54% comm.
The spread, freedom of sizing and comms based directly on size traded are one of the most important aspects for underfunded traders. Add to that that you have a large selection of currencies including exotics, and you can also trade CFD's for many US based futures. Yes the spreads on CFDs are not exchange like (i.e. 0.6-0.8 in ES, 0.06 in CL) so you are not going to scalp but your fills are guaranteed and again you can trade any size you wish including mini lots (or even 0.05 lots in futures) and pay comms accordingly.
You will also get free market data and some charting software for free. All of that will get you started and let you learn the markets, allowing you to make thousands of micro trades before you get wiped out and see how hard it is to make money in the markets.
In your particular situation, the only positive to trading directly on US exchanges would be avoiding income tax as US based brokers would report it to your tax authorities. But taxes on profits are not something you need to be concerned about at this point as you're not going to see profits for a long time. And everything else is against you: the bankroll is too small, product selection is limited (well you get spreads, options etc but again not for that kind of bankroll), sizing is full contracts only, just few 1/10th size, but comms are based per each car (so 2 micros=0.2, if available, means 2xcomms). Also you will need to pay for software and data feeds, both live and historical.
IMO you should start with a good ECNs broker for all the reasons explained above.
As far as the products and strategies, you can traded anything you want and anyway you want. In fact you should not copy anyone. Put up some work and research and get your feet wet. By trading 0.01 or 0.05 lots you stand a chance of trading long enough to find an instrument and strategy that fits you.
Once you get that down and are ready to put up some more money ($10k min), then you could move to US based exchanges, provided the products there are your choice.