Tank sizing for a pea puffer?

[tinypuff]

I currently have a 5 gal tank that's empty, well not so much empty but it doesn't have any fish in it. There are two anubias that have been anchored down to driftwood in there and I talk nicely to them so they don't die. It used to house a dwarf african frog for a month (I was watching someone's frog while they were moving and painting). My goal is to get a pea puffer...it's a fish I have always wanted to keep, ever since I went to the LFS and fell in love. I have been drifting through old posts here and the bare minimum that you guys are saying is a 5 gal but I am not a person who does the 'minimum' for my pets. My dog has 4 different beds, the cat has three plus a ton of Costco boxes he sleeps in...you see where I am going, I love my pets and I like to get them above and beyond their minimum. So here's my questions for you guys who keep the tiny puffers:

Would a single pea puffer be happier in a 5gal or a 10 gal tank?
Are they a spooky fish? Meaning, if it was a single puffer in a huge 10 gal tank all on his own (maybe some snails for dinner and a ghost shrimp or two that I am not attached to and can also be dinner) would it be too much room and cause it to stress out? Might sound weird but my old betta hated a 10 gal tank and he stressed out so bad because there was just too much space.
Food wise, it's snails and frozen bloodworms and maybe live blackworms if I can find them. Anything else to add to a diet that I should look for?
The filter inside the tank is a Tetra 10i whisper internal filter, it doesn't seem to move the water too much but there is a noticeable ripple at the top where it spills over. Will this be too much water current for a tiny puffer? Is there a filter I should look for instead?

Getting a 10 gal tank isn't that big of a deal. My problem with my current 5 gal tank is, I want to plant it. Like dirt with a cap and hopefully some good carpeting plants down. There isn't much room in the base foot print for planting a good amount of pants in there and I worry I'd crowd the tank up and not leave the puffer enough room for swimming and activities. The filter inside the 5 gal is a Tetra Whisper 10i and it takes up so much room it's not funny but the little filters for smaller tanks are a joke and I'd rather over filter than under. So another reason to go up to a 10 gal.

If any of you have planted tanks, what sort of plants should I keep an eye out for? I am still sort of new to the whole planting tank idea but I'd like to give it a shot, so hardy plants that I hopefully won't kill right off the bat would be good.

Sorry for the wall of text and thanks if you have any tips for a future puffer keeper!

[bertie 83]

A 5g would be ok for a dp, a 10g is perfect. As long as there is plenty of decor to explore the puffer will be happy on his own