Will it be possible to build up the units?

will there be options to upgrade infantry type units

Ground troops are not specifically "upgraded" as such, but when you invade a planet, there are various types of warfare that you choose from that offer different combat bonuses (varying in terms of the size of the combat bonus, the cost of using the type, and the damage it may do to the planet's buildings/population). In order to use any of these different warfare styles, of course, you need to have researched appropriate technologies.

is there an option to make an individual unit into something akin to a commander to help lead other troops with exceptional abilities?

Ships that win battles do gain in experience, which increases their hit points, and certain modules added to Starbases can increase the combat abilities of ships in the vicinity, but so far as I know there's no way to upgrade a particular ship to provide similiar bonuses, no.

- Ash

Your troops are upgradable en masse through research and random events but there are no individual units, as such.

Planet invasion is a short epic determined by invasion force strength against citizen soldiers based on planet population.

Bonuses to soldiering from either research or events is what to look for if you want your infantry beefed up.

Thanks that answers my Q's about that.
This is a really great game from everything I read and visually see here! I hope if becomes a classic!
D

There's also a racial bonus for soldiering I believe, courage. 1 point for 25% improvement.