traveling from US specifically for Panda facility. Which airport is the best to select and safest?

The best airport is CD Shuangliu Airport, but as I know, you need to have a transit at Beijing or Shanghai.
As for hotels, there are not many choices near the base. I happen to know a Xialingju Business Hotel in 1333 Xiongmao Avenue.

I found Ibis fairly accessible (4oom due north of Zoo station - exit C) and cheap. 198 bus runs past both Chengdu Zoo and Panda Avenue stations, and was actually the best way to get back to the Ibis (stop about 200m past). But it can be slow in peak hour, so if staying near Zoo station you can save time getting the metro 1 stop to Panda Ave.

They will try to steer you onto the "free" Pink Panther bus where you can "buy tix onboard." I played it safe, paying Y2 for the public 25 bus instead and bought my entry ticket at the venue. For Y10 more, pay for the golf cart ticket hop on / hop off inside the park as it can be a fair bit of walking.

If you can get a hotel at Panda Ave station, all the better - the 25 tourist bus is a shuttle so only takes a few minutes compared to the all-stops public bus. As the article says, airport line ends at Taipingyuan, change onto Line 3 - should be about an hour from airport to one of those two stations for Y7, forget about ripoff taxis. But after a 14 hour flight, you might prefer airport hotel and get the train from T1 or T2 Metro next day.

I believe United flies direct to CTU from SFO and Hainan Air to LAX. Hundreds of connecting flights - Kayak or Momondo can help.

Very hot in the northern summer.

If you're going just for the pandas, it MAY be possible to do it visa-free under the 72 hour rule. But there's lots more to see. Great Wall, Xian / Huashan mountain.