Hi,

We consider what are commonly referred to as Snowshoes as Half Siamese.

There is an official breed called Snowshoe, but you'll never find one, they are so rare.
What we call Snowshoe are Siamese crossed with an DSH bicolor, such as a Tuxedo.

Any dilution of the Siamese temperament will also tend to dilute the strong personality traits of the cat.
So, if you get a full bred Siamese cat, expect the rather high-strung, obsessive, dominant, needy personality.
Snowshoes are more mellow and accepting. More like the DSH.

It would be a toss up whether you get a male or female. I would lean toward another male, IF your male isn't really dominant and likely to spray or be territorial.

As a general rule, I wouldn't add another young female to your 2 young females. Keep a 5 year difference in cats of the same gender.

If I may, there is a rescue organization in CA. that specializes in Siamese and Siamese mixes.

siameserescue.org
the CA centers.

Thanks for rescuing and best of luck in finding your future Meezer!