This is basically what you can have and what you can't have.

Bloodlines
Anyone may have a bloodline with its respective clan.

**However, if you are a demon host, you may not have a bloodline.

All bloodline users start without access to the bloodline.

Activates after 10 attempts at learning access to the first stage of the bloodline.

Curse Marks
Anyone may have a curse mark.

Only one person per curse mark available.

**Demon hosts may not have a curse mark.

Curse mark effects must be activated during a life-threatening event.

Requires 10 attempts at activation to access the first stage of curse marks.

Transplant Doujutsu
Anyone can have these. However, you may only have one bloodline transplanted. It costs double chakra for the use of this.

And the chakra drain for the doujutsu is constant as well as double.

**Active at the state it was used previously.

Demons
Anyone except a Kage/Sannin may have a demon.

Demons may be extracted using forbidden techniques and placed into anyone save Kage/Sannin.

Demon hosts may never have a bloodline.

Eye transplants can be used for demon hosts.

Requires 10 attempts to learn how to control the demon at a single tail. Once the 2nd tail is reached, the demon is no longer controlled normally.

Summons
Anyone can learn a summoning technique at chuunin-rank. You only need a scroll of the original contract, and you may join it after learning the summon.

Requires 10 attempts at learning before the summoning is opened for use at its first stage.