total rookie, buying a helmet. What to look for?

Usually, the helmets that you like for bikes, will have a similar SA-rated helmet. If an Arai fits you well, they make SA-rated helmets, too. They'll have the same basic shape between M-rated and SA-rated helmets.

As far as added features, if you're serious about road racing buy what you can afford. Hydration, radio gear, safety gear, etc. is all worthwhile when you use it often enough. Are you just dipping a toe in the water to check the feel? Buy a cheaper helmet and sell it when you decide you want more, or you're going to get out.

The SA2020 helmets won't be out for at least 18 months. The SA2015 helmets will be good until 2025 for Lemons, unless the rules change.

Although watch out, because some companies, like Bell, are NOT the same between motorcycle and autosports. I’m a completely diffrent size in my Bell SA as I am in my Bell M and the overall fit is diffrent.

Bladder is one option.

Safety companies are making balaclavas and balaclava accessories that lift lids without the necessity of an inflator.

(not affiliated, yada yada)

https://www.stand21.com/products.r-2/un … avas.r-46/

https://www.youtube.com/watch?v=RaCXhsvAsGo

I recently bought a ZAMP RZ-44c carbon fiber helmet for desert racing since I needed  the ability to duct air into the helmet for desert racing. It's an SA2015 helmet that replaced my GForce SA2010 helmet. FWIW, I also wear glasses.

Both felt comfortable enough and similarly sized but the ZAMP was noticeably lighter. I paid about $375 delivered after eBay coupon (when they start feeling like they will be short on their revenue targets before EOQ, they often offer 15-20% off coupons for one day to juice up the volumes).

I'd totally buy another one.

PS. I was cleaning out my old helmets (I have a few extras from friends who like using my garage as storage) and even old, "obsolete" helmet have value to others (perhaps for track days or HPDEs). Last year, I think I sold a Pyrotect SA2005 open faced helmet (makes you look like a vintage rally nerd) for $35 and the GFORCE SA2010 helmet for $75.

If you have the chance to try helmets on... do it.   Not every helmet is shaped the same.  I have a $1300 Stilo with all the bells and whistles that I didn’t try on before I purchased.  I get a little hotspot on my forehead and after two hours in the car it can be painful.

The rules are clear that a Snell SA2010 helmet is still perfectly fine, although you'll probably need to drill a couple of holes to mount the neck restraint hardware as the holes aren't standard for that specification. The hardware comes with instructions for how to do this properly, so it really isn't a big deal. The SA2015 helmets don't typically come with neck hardware as standard anyway, just two pre-drilled holes, since the different models of restraints use different types of attachments.

If Lemons HQ follows previous practice, 2019 is most likely the last year for SA2010 but if you like the idea of trying out a helmet for not much money then there are probably good deals to be found for some decent but soon to be completely obsolete models.

I got my current SA2010 helmet before needing bifocals but I haven't noticed any particular issues now that I (sigh) have them.

Hate to ask, as a lifelong motorcyclist, have you tried the spoon method for removing the hotspot?

That said, my cheap helmet is too round and even with liberal spooning (yeah, jokes will come) I still get a hotspot about 2 hours in and it lasts about 30 minutes.

Pedantically sure. It's As safe as the standard.

If it lasts 4 hours, you should see a mechanic immediately - your giubo might come apart.