Vibrations and pulling to the left at 70mph normal?
 

I have an 01 Boxster, and under 70 it tracks straight with minimal vibration.

At 70 on the highway, I start to get more steering shimmy/vibration and the car seems to want to pull to the left.

Tire pressure is ok, had a shop check the suspension and that was ok.

Is thi normal at high speeds for the boxster, or are these symptoms of needing a balance or alignment?

Probably wheel balance. Alignment you'd see uneven tire wear and steering wheel off center.

A vibration is not normal.

I assume that you haven't taken the tire off recently. If you have, are you sure that you remounted the rim properly on the hub.

If the tire is mounted properly, check to see if the balance weight has fallen off the left front tire rim. If it has, then a re-balancing is in order. Re-balancing may be needed anyway if all of the suspension components are in good shape.

Sometimes a warped brake rotor will cause a shimmy. I would expect such a source to increase the vibrations as the speed increases.

It could be worn Brake pads, Wheel alignment & Rotors.

The same thing happened to me a couple of weeks ago I was driving along minding my own business and then all of a sudden the car veered to the left I thought I had a blown tire at first so I pulled over and to my surprise everything was intact then squeeking and grinding came later on and it turns out my brake pads and disc brakes are gone.

I am getting brake squeal when coming to a stop, so that may be it.

Yes that's most probably it.
Take it down to your local Mechanic and explain everything to him including the squeeking/grinding and he will have a look at it for you.

If it only pulls to the side over 70mph, does that rule out an alignment issue?

Check alignment first, especially the tow in-out for the pulling. Struts, control arm bushing and bent rim for the vibration.

Not necessarily

I would think the vibration indicated a tire balance, warped rotor or worn suspension problem. I would also think the pulling was an alignment, brake caliper / pad, or tire defect problem.

It may be that you see these symptoms at 70 because they become severe enough for you to feel the effects.

Most likely simply need a wheel balance (vibration) and an alignment (pulling) but the other possibility is wheel bearing (both). Raise the wheel off the deck and try to move it in and out. You should not feel any movement. Then push the brake pads back away from the disc and spin the wheel. Light scraping will be the brakes but there should be no rumbling or groaning. Movement and or noise means wheel bearings.

I figured it out - got a set of new tires, balanced and aligned the wheels. No more vibration at higher speeds, even though I still get feedback from the steering wheel, which I think is normal for this car.

Yes, lots of steering feedback is standard. Its a blessing when driving fast but can be a bit fatiguing on a long trip - so I just drive fast all of the time. :D