Learn Finnish: Se on ihan helppo homma. - It is quite an easy gig.

Yes, exactly! Homma is a very common colloquial word for a job, task, gig, or matter. In standard written Finnish (kirjakieli), you would use words like työ or tehtävä instead.

Why use ihan here instead of aika or todella?

In everyday Finnish, ihan is a very popular and flexible intensifier. While it often means quite or fairly (similar to aika), it can also mean totally or completely depending on your tone. Here, ihan helppo usually means quite easy or perfectly easy.

Why is helppo homma in the basic nominative case rather than the partitive?

We use the nominative case here because homma is a countable, singular noun. If you were describing an uncountable mass noun, you would need the partitive case, like in Se on vaikeaa työtä (It is difficult work). But for a single, countable gig, it stays in the nominative.

I know se means it, but does its usage change in spoken Finnish?

In this specific sentence, se simply means it, referring to the job. However, a major feature of spoken Finnish (puhekieli) is that se is also used for he or she, completely replacing the formal human pronoun hän in everyday speech.