Great to see another getting back into it.
Sump selection is a personal preference. Read lots. Deep sand beds are still in use. Miracle mud not so much. Many now prefer to just run Chaeto in what used to be a 'fuge and keep the sump 'clean'.
Your Bubble Magus Nac7 choice, I feel, will be too small for your 150g w/sump. Once you add a sump to it, you may want to look at something rated 50% or more higher than your total volume, like
this one ( just an example ).
For heaters, I dont' like using larger heaters due to cooking issues, but you may prefer to use titanium over glass. You may want to have your mains be a group of smaller ones, such as 4 x 200-250s. I'm basing this on 5w/g and you getting a 75g sump, so 225g total. Decide now what size you want for you 150g and you can add more later. A 200 will do it for your 45g, but you would need 4 more for the 150g. I like your idea of using a backup. I went crazy and have, with 110g total, 3 x 200watt on a RKE and 2 x 250w on a Ranco controller as backup.
Many will tell you live sand is a waste of money.
A single MP40wES is a good start with the 45g as you will need 2 of them in the 150g. Some say they are too noisy, but I like mine.
Radion is a great choice. There are others, but I have no experience to share.
Return pump selection will need to be based on the current tank, IMO.
I see you're in AB. Test your tapwater TDS and see if you need to have DI on your RO.
Hope that helps a bit. Good luck and post lots of pics
