How many millimeters thick is this suit? Thanks!!

I'm not sure how many mm, but I can say that the specific thickness may not matter if your underlying concern is whether you can stay dry and warm in near freezing conditions. The answer to THAT question is definitely yes. Unlike a wetsuit, where thickness is tied closely to warmth in specific water temperatures, a drysuit's main function is to keep you dry in wet conditions and give you flexibility to add layering according to your needs. This suit is roomy enough for you to put as much layering underneath as you want. I've used it with a single layer of clothing underneath in very cold conditions, and the wind/wet protection of the suit combined with heat generating activity (I standup paddle with my suit), are enough to keep me warm throughout my workout. I have a major caveat to give you about this suit though (and I'll probably put this in a separate review of the suit): The zipper works well as long as you keep it well lubricated with an appropriate zip lubricating product. It worked well for me last season with the lubricant on it, but this season I neglected to reapply the lubricant and the zipper failed to catch properly. Once it came of the zipper track, there was no way to get it back on track and I just sent it to O'Neill for a possible $100+ repair. UPDATED 12/15/2016: O'Neill responded to my repair request immediately and they just sent me a new suit, no charge, so I have NO complaints about their customer service on this issue! If you don't make my mistake and you lube it appropriately, it should work fine. The zipper is EXCLUDED from the manufacturer warranty, so you must pay attention to this issue or else pay for a repai

How much does it weigh? What is the best option for the feet?

It weighs less than three pounds. It doesn't weight any more than my regular wetsuit. They sell neoprene booties at most dive shops made out of wetsuit material with rubber soles. I use those with the dry suit. The ankle openings are tight so it doesn't let water up the legs. There is no 'dry shoe' option that I know of. I often wear my westuit under the dry suit for extra warmth.

Do you have 2xl for the boost drysuit?

The boost drysuit is not produced in size 2XL.

I'm thinking about buying a suit 561 75 should I get a medium or lodge

Can't answer that, sorry. I bought mine several years ago and like the suit. Very good size chart on their website. If unsure, error on the large side.