Yes.
Keratin treatments will not work on already relaxed hair. Applying this treatment to relaxed hair could result in breakage and damage to your hair.
Yes, but not shortly after.
yes
Yes
About 2 weeks to a month I think... ( '_')
You can straighten your hair whether or not it is relaxed.
No, you do not have to cut your hair. You can simply stop getting relaxers. To avoid a rough transition, though, you should get sew ins until your transition is complete. If your hair is currently relaxed, then you will need to cut off the relaxed parts. You may grow your hair out of about 4-6 months before cutting the relaxed parts, but if you don't cut it, it will soon break off at the demarcation line (the point where the stronger natural hair meets the more fragile relaxed hair)
The answer is yes & no. No matter if you have natural hair or relaxed hair if you don't take the time to properly care for it will be unhealthy. There are benefits to natural hair and relaxed hair but it really depends on your preference. Choose the option that best for you.
You have two options. To grow it out or cut off the relaxed hair.
Advantages of getting your hair relaxed is that it will look better and be more manageable, these are short term though. The disadvantage of this change is that you are putting chemicals on your hair that will damage it and in the long term be less manageable until you cut it off.
That depends on how frequently you do it. You hair does not become "un-relaxed" after time. You have to touch-up the newgrowth & if you want your hair "out," you have to cut your hair.
It shouldn't be needed, but you can; however, do not do it shortly after as the hair is already somewhat damaged from being relaxed.