Clearance above boiler and short feed

I have two questions I need a bit of help on!

I am installin my boiler in the basement of my old farm house. I don't have alot of space unfortunetly.

After putting the boiler up on 2" bricks That leaves me with only 15" of clearance from the top of the boiler to the bottom of the floor joists. Is this going to be an issue for piping or any code?

My boiler is a high boy so its I think about 7" taller than a standard DF520 model. I don't know if I'll have to put up some type of flame or heat retardant material above the boiler?

Second I will have only about 6" of clearance to the stone wall of an inside corner in my basement. Once again is this an issue? its all stone foundation so not flamable.

My boiler will have no sides or insulation on it. I want some heat to radiate into the basement as there is no heat down there currently. So I am fine with that.

Lastly on the feed tube side. I have 2 options. Feed into the bin and that is probably about 3.5' of feed pipe or feed into a barrel which would reduce my feed to about 2'. I have read where people feed with just the short tube into the barrel and mine would be a TOUCH longer than that.

Just curious if this is still safe as far as CO2 leakage or what I need to do to prevent it with this setup.

Thanks for all your help on these questions!

Mark Check your PM's

However you set up your bin, you should have no more than about 4" of worm into the coal. Use a sealed lid for the top of your barrel.