You can’t choose the currency when you sell (at least I’m not aware of a broker that allows that). However, if it’s the exact same fund and share class (same ISIN), you can instruct a broker to e.g. change the EUR position of that ISIN into a CHF position without any trading. Swissquote charges a flat fee of CHF 50 for that (per position). If the position is large enough and you would otherwise pay high currency exchange fees, this could make sense. However, if you only have a few EUR shares and your broker offers reasonable exchange fees, just convert the cash after selling the funds.
An ETF tracking the MSCI EM index would be the obvious choice. And maybe a small allocation to an SPI ETF if you want a home bias, but this is completely optional. Check justETF for a good overview of ETFs. There are various other ETFs (maybe different asset classes such as real estate, gold/commodities, bonds) you could add but I can’t say what makes sense in your individual case.
I’m not sure what exactly you’re asking. Trading currency on its own is irrelevant (except for currency exchange costs). I would advise against hedged ETFs with the exception of bond ETFs (if you want international bond exposure). Currency exposure and ETF may be useful to you.