Is the word growing future tense?

Answer 1

No. It is a present participle.

The word 'growing' can be a participle or a gerund, depending on how it is used. If used as an adjective, it is a participle. Think of it as a verbal adjective. If used as a noun it is a gerund. Think of it as a verbal noun.

Participle: "This is a growing site, because it gets more and more questions."

Gerund: "Growing, for a site like this, requires getting more and more questions."

Answer 2

No, "growing" is not in future tense. In this context, "growing" is a present participle used to describe ongoing or continuous action in the present.