Primary and Secondary vessels

My process has always been (although very limited) primary fermentation only. I have only 2 containers: primary plastic tub and bottling tub (both made by true brew).

That being said, here's my question. If I wanted to do a 2 stage fermentation, could I used my bottling tub for primary, rack into my plain fermenter bucket for a secondary, and then rack (again) into my bottling bucket for bottling?

Do I HAVE to use a carboy for secondary fermentation?

Thanks in advance.

you can definitely use your bottling bucket as a fermentor

Not really, though for a long sit in secondary (over 2-3 weeks) I'd be more comfortable with glass over plastic. For a couple of weeks I'm sure it would be fine.

I've considered using my bottling bucket as a primary, but decided against it mostly because of the spigot - possible sanitation issues, chance of beer leaking out, etc. I use 5g glass carboys for secondaries, and since I always have 2 brews going at once I didn't want to tie up my bottling bucket. Honestly it would just be easier to do a long primary (3-4 weeks), and one of these days I'll probably just make another primary. Icing buckets from the grocery store bakery can usually be had for free, have a good tight lid and all it takes is a hole in the lid for a stopper and airlock.

I generaly don't use secondary.

When to go from Primary to Secondary (If at all)

I usually do not use a secondary, but have on a few occasions (adding flavoring to beer). I contemplated using my bottling bucket for a fermenter but I would just spend the extra money and get another bucket or glass carboy.

Only using glass for secondary? I've asked my local brewing store owner and he says it is only bad to bulk age in a bucket if you are doing a strong beer or apfelwein.