1. How long did it take for a transaction to be confirmed?
Transactions before were so quick that it won't take 2 minutes IIRC and I was able to catch up those days that there's no fee when you send bitcoin. It is because there were few users unlike today.
2. What were the other issues experienced apart from Hardware complications and energy requirements?
Can't say on this matter but before the earliest time, you can mine even with your laptop.