plain and polite verb suffixes

[Fociis]

Are all verb suffixes that are added on to the plain (dictionary) form also allowed to follow the polite form of the verb? Are there any hard and fast rules governing them?

Ex:
plain + kara = polite (-masu) + kara
-deshou, -hazu, -hou ga ii, -made, -tame ni, etc...

 

[PaulTB]

Are all verb suffixes that are added on to the plain (dictionary) form also allowed to follow the polite form of the verb? Are there any hard and fast rules governing them?
Ex:
plain + kara = polite (-masu) + kara
-deshou, -hazu, -hou ga ii, -made, -tame ni, etc...

All allowed, some more common than others, no hard and fast rules ... would be my summary.

Unless you are in a particularly formal situation then using plain+○○ should be fine for everything apart from the end of sentences.