Kris,
If you’ve never dealt with this stuff before, you may just want to contract it all out to a qualified post house. For example, you didn’t even mention closed captioning, which is required by most buyers (certainly by ALL broadcasters).
You don’t comment on the audio specs. Most broadcasters want Dolby AC-3 encoding. International audio specs are always different than domestic, and require special treatment (fully filled M & E), unique track assignments etc.
If you’re delivering to a buyer, they will have pages and pages of tech specs for you to follow. I’d suggest you get ahold of that document and make your decisions based on what they require.
As for the rest of your plan, it sounds like you’re chasing your tail! Outputing SD, up converting, new titles in HD, this all sounds way out of whack! I don’t follow why you’re going up to HD, and then back down to create a master. You really have to follow a dual path here. Your timeline is SD. Use that to create your SD masters, both texted and textless. If you want to use the terranex to upconvert, go ahead, but that master now has NOTHING to do with your original SD source.
Finally, a friendly word of advice. You admit that you’re new to this part of the process. This is NOT simple stuff. You’re dealing with extremely specific tech specs that require a strong base of knowledge to get it right. The cost of rejected masters will quickly erase any saving that you’re trying to make by doing it yourself. If you don’t have HD capable scopes to monitor this process, you’re really treading on thin ice.
Good luck.
Mark