I do BIAB all-grain in 1 10g Aluminum pot with no spigot...so you should definitely be able to do that.
If you want the full 3-tier, again I am sure you can set it up for that, but it will involve some work.
As far as keeping mash temps, I use 1 old polar-fleece blanket that was just sitting aorund the house not used anymore. I fold it over on itself about 4 times, and loosely bungee it around my brew kettle (all around the sides and over the top, bottom is exposed, but it is on the warm stove...), I lose 1-2* tops over an hour like this, which is good enough for me.
Honestly, it is surprisingly easy once you get your process dialed in and get used to your equipment. Everything after the mash works exactly the same, and mashing isn't anything really crazy. You will need a good thermometer...and it takes longer to cool full-boil batches, but that is about it.
That is my take anyways, to each his own.