I am adding a 60 Amp sub panel in my attached garage to run a few tools. Currently there is only 1 15 Amp circuit feeding the garage and is over taxed and I need to be careful what I turn on .

The main service is on fuses and had a hard time finding a double buss block for the panel.
The new panel has no main shut off and my plan is to put in 2 15 amp circuits, 1 for lights and 1 for plugs.
I am also putting in a 20 amp twist plug for a heater.
I have purchased NMD 90 #6 - 3 for the feed. I have read on a previous post that a nipple through the foundation is Ok. Does the cable need to be in a pipe to the sub panel?
Can I use NMD 90 (Romex) in the garage ? Currently there is both Romex and Bx.
I also read " not " to strap the ground to neutral as this is still in the same structure.

Thoughts comments are welcome!!
I am in Brampton , Ontario