I am 23, foreign student as well and in Grad school. I got my first no annual-fee card in 2007 (age 19), slowly built history around 3 no annual fee cards (Chase Student, HSBC Cash or Fly, AMEX Blue Sky[with $8100 limit!]) all opened in 2007. Then in 2009 I got the Discover More, Citi Forward, and Delta AMEX Gold. I also got 2 store cards at some point as I read somewhere lenders want to see "mix" of credit and that counted. Late 2010 till now, I started this mileage-earning-card-applying game. Have gotten 3 Citi AA cards, Chase CO, Chase British Airways, CapitalOne Venture, Delta AMEX Gold Business, and AMEX Platinum charge.

Credit score still in mid-700s. As you can see, number of cards doesn't really matter. When your credit history is short, what matters is your relationship with the banks and the age of your oldest card (average age of cards plays a smaller factor), given you have solid debt/income ratio (my income was around 30k a year too) and no negative stuff. I built relationship with each bank with no annual fee cards, never missing a payment, never carrying a balance. This built my history AND my worthiness to them, which greatly increased my chances of getting approved for future cards with them. It was hard to get certain cards at first, especially with Citi for me, but once you get and have a good record with them, you're "in." Of course that's given that your credit score is still good and history is good and all that.

To answer your questions:
1) Sometimes credit limit increases don't result in hard pulls. Ask first. I noticed that inquiries played a bigger factor when I first started out, not so much later on, but if you're not doing 5+ a month, you're ok. Also, depending on where you are, different banks pull from different bureaus in different states. I believe AMEX and Chase pulls from different bureaus where I am, so even if both actions result in hard pulls, they may not be as bad as you think.

2) I would hold off on the SPG for a couple reasons. First, because I think there can be better SPG sign-up offers in the future, like the one last year with 35k(?) I believe it was? Second, I think you should have one or two more no-annual-fee cards, if you eventually want to go the AMEX route, which you should because their CS is by far the best, I would suggest the Blue, Blue Cash, Blue Sky, or Hilton as mentioned.

Blue for Membership Rewards: you can't transfer to airlines or hotels with this tier of MR membership, but if you later on get a charge card, the MR account can be merged. And when you cancel the charge card, you don't lose all the MR points.

Blue cash: NEW Blue Cash Everyday & Blue Cash Preferred cards

Blue Sky: $100 statement credit on any travel purchase after $7500 spend. A 1.33% return rate.

These are suggestions based on my experiences and hopefully you can relate to it. Of course they may not suit you and YMMV. Feel free to PM me for more.

You should also checkout http://www.frugaltravelguy.com. Lots of great advice. I can send you links to some useful posts on his blog if you like.