I personally would start with the eel as they are much hardier than a lion. My first fish was a 6in snowflake that out lived 10 other fish as I learned this new hobby. I got to used to him being at the bottom all the time and for the first time I was trying to go topless on his tank because he never came up to the top so I figured it was safe and the first night he jumped and expired during the night. So if youre gonna have an eel make sure you have a top on your tank.
With the lion I would wait a little while and see if you can keep the eel and maybe another fish alive for a few weeks. Anemones are kinda touchy creatures, you gotta be careful of overflows, powerheads, rocks, pumps, and any moving parts. They also need fairly decent lighting. Anyway I wish you the best with the setup but make sure you take it slow. Im waiting right now for my big tank to cycle so my shark, stingray, and lions can have plenty of room to roam and it is a constant want to put them in right now but it needs to cycle so that im sure im not gonna kill them with the unstability of a uncycled tank.