IF you transfer the ETH to him, and he hands you cash, the IRS would have no idea you made money, and whiel you would be required to claim it on your taxes, the IRS would have no idea the event ever happened. However if you took that cash and started depositing it on a regular basis, your bank might flag your account for review and you could be expected to claim the income.
There are a ton of alt-coins to mine. Picking one can be difficult. There are a bunch of GPUs to choose, if they are even in stock. Pretty much any gpu with over 4 ggigs of ddr5 will mine any alt coin. There is no one answer because there are so many possibilities. Do your research, use Google, read the forums, and realize that everything you learn cam change daily.
Yes, sort of. You can setup a coinhive account which creates a website you can log into with your phone or mobile device. But, depending on your mobile device your hashrate will be so low it would never be worth it. Currently they pay 0.00006119 xmr per 1 million hashes. My Samsung S8 will of 20 H/sec. If I had my new s8 hash 24/7 265 days a year I would make 0.038 xmr, or about 13 dollars. I tried it with a old Windows phone and a Samsung Tab 3. The Tab 3 wouldn't hash and the Windows phone gave me 8 H/sec.
Have you tried unplugging all the cards but 1 and see if it a problem related to one card? Does the system crash or is it still usable? When it crashes are all the cards still listed in the device manager?
I worked as a Process Engineer for Intel for about 3 years. My duties included data mining and trying to find correlations between datasets. I know CPUs ate different than GPUs but the process is more or less the same. There was very little correlation between yield and bin and position on the water. It really was just luck with where defects landed and what kind of defects that existed.