Helmet is a complete must. They are the seatbelts of our age - we will look back in 20 years time in wonderment that people could have been so reckless as to not use them. Make sure it fits properly. Everything else is secondary.
Don't buy those awful sweat-inducing nylon ski socks. A thin pair of silk ones, or even cotton ones will be fine unless you are prone to poor circulation. They do need to be high, though, to stop the chafing around your shins.
Salopettes with braces are a no-no - too difficult to go to the loo. Regular pants fine.
So... soft-shell pants, soft shell top, and maybe a long-sleeved tee shirt underneath it. Vest if it's below minus 5 or so (unlikely this Easter, with it being late).
My advice would be: keep gear to a minimum. If there is anything likely to put you off skiing for life, it's the feeling that you have to remember about a million and one bits of kit before setting off.
Goggles are IME not necessary unless you are skiing in powder. I never get why people wear these. Shatter-proof sunnies on a retainer are fine. If you're wearing a helmet the glasses over-ear bits will be inside your helmet in any case.
If you have hiking boots, these will be fine for walking around in the snow. Streets may well be clear in April anyway.
You don't need anything special for apres ski - just whatever you fancy wearing.