Hello and welcome to BW forums
It's great to hear that starting EASY has had such a great effect, what a difference!
Getting out and about can be very hard for some LOs. Some seem to manage just fine and love to be out, they appear to be able to nap anywhere and without any fuss at all, don't be fooled by that though, the same LOs might be up half the night screaming. The key really is to work out what suits your LO and to work out a routine which is some sort of compromise or best fit between your needs and LOs needs.
As he is still very young and his A times are short it can be a bit harder to fit those baby classes or trips to the restaurant in, you might find a class which fits well with your current routine or you might decide to give it a miss until he is a bit older and can manage the class without having too much of a negative effect on him. He might love the class so you might feel it is worth the resulting disturbed naps for that day or he might be so fussy and vomiting afterwards that it's just not worth it. Or, you might find he can do a half class and you excuse yourselves before the end, get him in his pram for a nap and you both get the benefit of being out without so much disturbance and upset.
As he falls to sleep in the pram pretty well when walking I'd probably try to time restaurant (or any) trips so that you can get him started on a nap and then go the the restaurant and let him to sleep in the pram near you. I had a LO who would not sleep in the pram and I always wished he would so that I had a bit more flexibility for going out so I think it's a reasonable habit to continue if you can.
You might be able to plan out a routine whereby you always do the first nap or 2 at home, go out for a pram nap and a baby class or lunch etc with a pram nap or two with an A time between before heading home. Babies do well with predictable routines so if you can keep every day pretty much the same he will get into the habit of a cot nap at home in the morning and a pram nap out and about later on (or vice-versa).
These out and about parts of the routine can sometimes have drawbacks too of course. Mine was in the habit of morning nap in the cot then car nap on the way to an activity, A time at the activity then back in the car for the next nap time and to drive home. This really helped to get out but the problem I found was that on a day I didn't want to go out he would be very hard to get down for a nap at home - he was waiting to get into the car and I had to work much harder to get him in the cot. I also ended up trapped in the car quite a lot whilst he slept as I couldn't transfer him. Pros and cons really.
The thing with classes is that they are at set times, you can arrive late or excuse yourself early (and people do) but if you've signed up for a block you probably feel obliged to attend. Some are more of a drop in type set up where you might feel more comfortable to arrive late or just not go that week. Baby groups were important to me, I felt I really needed to get out and have a bit of contact with other mums. I suppose the thing is to work out which are suitable at this age and which to just skip for now. It gets easier when they are a bit older and the A time is longer too.
hope this helps some