Beginner here, if I wanted to keep my poodle hair longer or cut the least hair off, what size blade should I use?

6 types (3 mm/6 mm/9 mm/12 mm/18 mm/24 mm)

3mm is used for shave short coats. reduce discomfort during the hot season.

9mm trim maintains a medium length.

12mm trim will keep the longer coat. maintain a certain amount of curl and fluffiness.

Can this product be charged is 110v or 220v ?

110v

Will these work on a cat and horses?

Yes Just as useful

How do I clean this?

Use the brush to clean the blade. You can also remove the blade from the clippers and clean it with running water