But isn't stepping with the lead foot first basically the same as forward tsugi ashi?
Nagashi reminds me of rolling with a punch or a shoulder roll that sets up a counter.
Hiraki is sort of like side-stepping to cut off the ring or set up a better angle. So say you're right handed and you're sparring a hypothetical southpaw opponent, you want your lead foot to be outside his lead foot to land a straight right. A short side-step puts you in that position, so can Soto Irimi if you're on the outside.
A short Irimi is like a step jab while a long Irimi is moving inside to clinch or work the body.
Irimi senkai is a way to turn your opponent for better position if you are cornered, for example.
One problem is the lack of a consistent naming convention for steps/footwork in Aikido, as they tend to vary... or be as generic as just saying tai-sabaki for everything.
Makes it difficult sometimes in communicating points - [unless, with what you did, you describe each step]
We have 7 steps/footwork our 6kyus have to learn, which apply to the techniques themselves... and a couple of those have 2-3 variations to them. [the ones that specifically deal with weapons]