Wish I had the D series video edited but I’ve just been too busy lately. I’ll answer your questions in order.
You will need to support the engine with a floor jack with a wood block when you take that mount loose to replace the belt. Just remove the mount, you don’t need to jack the engine way up to do this.
I would just remove the valve cover completely to remove the upper timing belt cover. As for the problems you’re having with that just leave the rubber in place and pry up on the valve cover after you remove all the fasteners. The rubber may or may not pop out, it really doesn’t matter. Just make sure you get them back in when you reassemble.
If the cam seal is not leaking leave it alone. If you replace it and you don’t get it in properly or you use a part that’s not OE then you may actually create a leak.
You should not need to drain the engine oil to do any part of a timing belt job including replacing seals.
The crank bolt is the FIRST thing you should do. If you can’t get that loose you’re done and it’s a waste of time to do anything else. I can normally break it loose with an impact. Do not use a chain wrench or anything to hold the pulley in place, it’s cheap metal and will break if you do this. Try wedging something in the flywheel to keep the engine from turning to break it loose if you don’t have an impact gun.