Electrum wallet is an open source wallet and has been well reviewed, but ElectrumABC[1]'s version has not been reviewed like Bitcoin version, although it is open source and looks good in general.
you can also try https://viawallet.com/ which is another good option.
about Mining it you can read this ----> https://bitcointalksearch.org/topic/m.57585522 or PM @philipma1957 he has previous experience with mining it and may help you (be nice when asking)
[1] https://github.com/bitcoin-abc/ElectrumABC/
https://coin.fyi/news/ecash/storing-ecash-xec-coin-on-hardware-wallets-sfe32c
Might be useful for another newbies reading through here, thanks @hugeblack