Rain Hat/Hood/Cowl for roof vent pipes

[Prosper]

Over 30 years in this house and only now noticed that there is no Cowls on the kitchen and bathroom vent pipe terminals on the roof. There is one on the third vent pipe terminal for the sewage vent pipe which I wouldn't have thought needed it. I only noticed all this when looking at a Google satellite view of the roof. Of course with my luck I only noticed after I had installed new extractor fan in both kitchen and bathroom and after wrapping with insulation the exposed sections of the pipes in the attic.
It's about 15 years since I was up on the roof but I still think I'd be ok doing the work myself.

1. Any recommendations for types of pipe terminal covers to use would be appreciated?
2. I'd probably use a Tec7 or Bostic sealant/adhesive, as I have these already, but if anyone thinks something else suits the application better then please let me know
3. While I'm up there I'll check the seal around each pipe where they intersect with the roof tiles. Any suggestions on what to use for this?

 

[Smaug~~°w°~~]

It's about 15 years since I was up on the roof but I still think I'd be ok doing the work myself

No idea what you should do about your pipes but definitely don't attempt doing this on your own. "I still think I'd be ok" doesn't instill confidence. Another person can, at a minimum, hold the ladder but more importantly they're their to call an ambulance if necessary.
Best of luck