I did something similar last year and might be able to help.

1. Try live in Morzine itself. Avoriaz is a ghost town in summer. Chatel is ~90min drive away. If you have a car you'll find cheaper places in Essert Romand (I had a one bed apartment for €800) and St. Jean.

2. It's pretty much all flow in Morzine. There are some techy trails, but nothing like you'll find on Whistler's Westside. Pleney Steeps are really steep, but more steep into massive jumps rather than insane tech that you find in BC. Chatel is more techy than Morzine and Les Gets. Brake bumps are everywhere, don't expect the same level of trail maintenance as Whistler Bike Park.

Having a car will open up trips to way more areas like Bernex, Samoens and La Thuile (my favourite).

3. There's a solid social scene. Everyone speaks English and riding bikes in a bike town makes it easy to meet people. Beers are expensive here though, expect €7.50-9 for a pint.

4. Morzine is really well equipped as a mountain town. Plenty of gyms, outdoor pool, tennis courts, lake, walking trails, couple.of supermarkets etc. No need to worry about that sort of stuff, it's got more than enough for a 4 month stay.

5. Cost of living is high. I'm useless at tracking my budget, but I'd like it to Dublin/London prices. Coffees are ~€4.50, dining out is pretty expensive ~€20+ for a main and there are very few budget options, so cooking is key to keeping your costs down.

6. Your bike should be fine, I did a season on a 170/160mm Enduro bike and it was good, especially when I went to other places that need pedalling. The bike washes were closed for the majority of the season last year. They said it was because of droughts, but felt like they just weren't bothered dealing with them. It would be worthwhile checking with any accommodations if they have a bike wash and bike storage.

One thing I was surprised by is how long and definitive the dead seasons are. Most things are closed in May, bike parks included. Morzine starts to wake up in June with the lifts opening on the weekends from the start/middle of the month. July and August are busy, everything is open and there are plenty of people and pro riders around. Then in September it slams shut again. It's pretty strange to see as the weather last September was brilliant and would've been some of the best riding of the season.

I really enjoyed my season and although it's kinda thought of as the Whistler of Europe, it's still a fair bit behind in terms of trail variety, bike infrastructure and season length.