Thanks for the information. The internship will be based at the EPFL so I could live outside the centre on that side of Lausanne. Do many people cycle around the city? I'm used to cycling everywhere so would prefer that instead of paying for the train, unless its hugely problematic or dangerous.

As for the advice on health insurance...I will enquire with the employer about it. If I'm lucky my current health insurance will cover me in Switzerland, seems like that would save me a fair amount.

Cycling is not that problematic, but not great either. Note that Lausanne is quite hilly and lots of climbing involved - but less on the EPFL side.
The fact that your insurance covers you here may not prevent you from being required to get a swiss one anyway. Legally anyone resident in Switzerland over 3 months have to get the local insurance, with very few exceptions...

I don't see why cycling couldn't be a possibility. I don't see a whole heap of them around, and I'm not sure what the overall perception towards cyclists are in Lausanne, but as long as you aren't annoying anyone whilst riding your bike I don't see the problem.

Lausanne is sometimes called the San Francisco of Switzerland. In reality, it's not too big a deal (so it seems) if you are travelling parallel to the shoreline. It's been said that riding along the lake shore is very pleasurable. Once you go perpendicular, things get a bit more interesting. If you have strong legs, climb mountains or so on, you might just find it all a piece of cake anyway, but you'll find out soon enough.

Of course if you live close to EPFL, you might rarely need to go into Lausanne anyway, viz. get all you need around Renens and possibly Prilly/Malley.

Flats that are rented to students in Lausanne normally need a Swiss garantor.

You certainly can get by with a bike- until the weather is bad but near the epfl its flat and even still plenty of people ride up the hills here. Lugano and lausanne prices are VERY different so beware of people outside of lausanne saying itll be ok or whatever- prices vary greatly. Even if living outside the center or near the epfl- youll have high rentals- the 800 i quoted was from epfl student housing so that is just for students- most other rents- including just rooms- are higher.