Double glass is usually sufficient as opposed to triple glass (depending on weather and noice conditions), but I would recommend a thicker glass (usually it is 3mm, but upgrading to 4mm glass would not cost much more and it would provide better insulation and resistance to accidental breakage).if you need any more info, just ask

If that person fails, the project fails...that shouldn't be the case.To be honest, having worked in that field to the highest level, the failure of the PM speaks more to your systems than it does to their competence.

They could learn that FHA will finance up to 4 units, get all their income documentation in place, get their credit score improved to the proper level, get the seller to do the required repairs, get funds properly gifted for their down payment, contest a bad appraisal and get it revised, and think their good to go......then they find out that while FHA finances up to 4 units, they have to be owner occupied, and the buyer can't do that so the deal is dead and all the work was for nothing.

I keep going and having that property enforced it to a whole new level.

I am considering purchasing an 11-unit mixed use (10 residential and one street level bar/restaurant unit). 

If you are still tax positive (not sure if term is correct), check with your accountant to see what other business you can use against the property.Depending on your gross income level and how you manage your property, you may not be able to write off anything on your other income from the tax loss of your property.

We have done very well for ourselves in our properties but want to take it to the next level.

What is your level of business knowledge currently?

.#3 is fairly passive if you have a good turnkey company, good location and a good PM.Of course #4 is all you although you could partner up with someone else.So it comes down to your goals, the level of passive vs active investor that you want to be, your resources(Time , Money, Experience).Your choices will depend on your goals. 

Given your W2 income, early withdraws from those accounts will likely kill you (its taxed at your ordinary income level plus a 10% withdraw penalty).