Hello,Mr.MASUKCHINA
This is my answer to your questions, hope it may help.
1)There are Youth Hostels in Chengdu. Check Dragon Twon International Youth Hostel, Chengdu Traffic Youth Hostel, and Chengdu Dreams Travel International Youth Hostel.
2)You can transfer between Chengdu and Jiuzhaigou by air or bus.
The flight fare is RMB1000 and the journey time is 40 minutes. The bus fare is RMB125, and the journey time is about 10 hours. Flight is fast and expensive while bus is slow and cheap. I suggest you take flight as it is faster and safter than take bus.
3)You can find all kinds of hotels in Jiuzhaigou, ranging from five-star to one-star. Youth Hostels like Caogenrenjia and Langjiezhiju takes 30RMB to 80RMB, which is located just outside Jiuzhaigou Scenic Area.
4)About your route in Chengdu and Jiuzhaigou, here is my suggestion:
July.6th Chengdu: Wuhouci Dufucaotang
July.7th Chengdu: Qingchengshan Dujiangyan
July.8th Jiuzhaigou
July.9th Jiuzhaigou: Munigou
July.10th Jiuzhaigou: Huanglong
July.11th Chengdu: Wenshuyuan Chunxilu

I want to thank Carmen 01 for giving me such a good advise.

As I have never been to these parts of China before except through the pages of the National Geographic Magazine recently (on Jiuzhaigou), please pardon me if I ask further questions which may sound like a hill-billy to seasoned travellers.

1. What is there to see in Wuhouci Dufucaotang? Will I be able to see the Giant Pandas there? Our flight will arrive in Chengdu at about 3 p.m on the first day.

2. What about toilets in Jiuzhaigou area. Are they tourist friendly. All these years, my wife is afraid to visit rural China because she heard that the toilets are not clean.

3. I can see that Carmen 01 has reccommended for us to see Jiuzhaigou for 3 days and Chengdu for 3 days. I have not heard about the scenic areas in Chengdu. Should I spend more days in Jiuzhaigou. The flight to Jiuzhaigou from Chengdu is so much more expensive than my flight from Malaysia to Chengdu. Maybe, I ought to spend more time in Jiuzhaigou . Is that reccommended?

I really appreciate Carmen's advise. Really. Thank you.

Hello,again.
It is definitely ok for you to spend more days in Jiuzhaigou. You may spend as long as 5 days to have a thorough visit.
As for what bothers your wife, i would say that toilets are better than before, but you cann't think highly of them.
If your point of this plan is Jiuzhaigou, you can skip Chengdu. However, Panda, as you said, is not a thing to miss. You may have a trip to Panda Research Center at Chengdu before or after your Jiuzhaigou trip.

The toilets in Jiuzhaigou are very clean! A new coat of plastic automatically covers the seat for every user. Public toilets along the road and near cheap restaurants are not good. Hotel toilets are fine.

Jiuzhaigou, as Carmen said, has a full range of accommodation. If you want 5* there is the Sheraton and the Intercontinental. I would personally recommend the only home stay there.