Helmet choice is somewhat personal..I prefer a 3/4 helmet and use a windscreen on my Savage.  if your young and somewhat inexperienced, you might consider a full face- they offer greater protection should you and the bike part ways while riding.  And as suggested above, try them on and get one that fits comfortably.
Enjoy your ride.

My older son and I have full face helmets, My wife and younger son have flip ups.

Advantage to the Full face for lightness and quieter while riding. Advantage to the flip up for people who wear glasses or when fueling etc. in the summer when you don't want to take off your helmet, but it's really hot out. Bottom line you can't really go wrong with either, so it becomes personal preference.

As far as any helmet without a chin strap, every FF helmet that I've seen that was involved in a collision had a big set of scrapes across the chin and cheek. Not surprisingly the riders that I know that hit their head without a FF helmet had corresponding scrapes on their face or worse.

I ride my '87 Savage around at 70 mph all the time.  That is the speed limit here.  I have run it down the freeway at 75-80 and it never even wheezed.  I've noticed with mine that it just goes and goes right up until about 85 mph, then stops climbing all of a sudden.  No rough or weak running prior to top speed.  Me thinks the guy who told you the Savage wouldn't hack it either has never ridden one, or wants to sell you something else.  I'm 6'-3" and around 185, by the way.  My freeway trip included about 50 pounds of gear.

As for the helmet I wear a full-face HJC that I paid something like $120 for.  I like it.  It's comfortable, well ventilated, and bug and rock proof.  Hopefully, I'll never have to find out how strong it is.

FCrash statistics show helmet damage. I had a regular Ol Helmet with face shield, till a guy explained how many crashes take the riders chin off. Then I bought a flip face. Then I stuffed my vface in the cab corner of a smnall pickiup, Anything less than full foverage would have been big time pain, possibly dead,

To be fair, I wasn't even wearing a helmet the first 2 tiomes I totalled a bike & the first time, IF I had been wearing one, I would be so dead it aint funny, cuz it would have broken my neck, as it is I had 3 cracked vertebrae, a helmet for a fulcrum between shoulder & head & POP,, dead, so, you pays your money & you tyakes your chances, Im sticking with the flip face.

OK, just to totally confuse you, there are actually three certifications:  DOT, Snell and EC (European).  Here's a brief rundown on the differences.

Snell:  Is a private foundation, and a Snell helmet is the only one you can use on a track day.  These must be full face.  Snell does not certify a flip front, period.  Snell also developed from motorsports, both automotive and the two-wheeled variety.  Snell also has a "double impact" requirement that requires a "harder" type of foam energy absorber than the others.  Receiving two impacts at the same location is far more likely to occur to someone who is strapped into a roll cage than bouncing off a motorcycle.  That's why there are some who feel the Snell foam is "harder" than necessary or ideally desirable.

EC:  This is the European standard.  They do certify flip up helmets.  I'm not positive, but I strongly suspect that that includes some type of standard for the latching mechanism.  The impact absorbing foam is midway between the DOT and Snell standards.

DOT:  Anything less is sold as a "novelty helmet".  DOT will certify pudding bowls and beanies -- which use air as a protective material in many critical places.  However, testing has shown that for the areas actually protected by a particular DOT helmet, the "softer" foam may well be an advantage in minimizing injury.  There is not, to my knowledge, any standard for latches on the flip-up style.

My opinion:  Full-face.  Go for fit, ventilation and comfort.   The best helmet is the one you actually wear, so if you find a full-face that you like, it's your best choice.  DOT, EC or Snell don't appear to be critical in this category, unless you want to do a track day.  

That said, I use a flip-up around town.  It's just easier to use with glasses.  For flip-up, go EC standard.  

If you absolutely, positively go bat-shot claustrophobic in a full-face, well, then you're looking at a 3/4.  Stay away from shorties, beanies and other "make-believe".