8 days in Kyushu

Could any one can advise for our trips as below:
03/10 Tokyo to Fukuoka by air
04/10 Fukuoka to Mt Aso ( by train, bus) and over night at Yufuin. Is one day enough in Mt. Aso?
05/10 Kuju mountain range by bus and over night at Yufuin. Is one day enough to cover both view point from Makinoto Pass and Chojabaru Visitor Center? Any nearby train go to Kuji mountain?
06/10 Yufuin for a day trip (by train and bus) and travel to Beppu
07/10 Beppu - the Eight Hells-Fukuoka (by bus and train)
08/10 Fukuoka - Huis Ten Bosch - Nagasaki - Nagasaki Kunchi (should we visit the 1st of Nagasaki kunchi festival?
09/10 Nagasaki - city tour in Nagasaki
10/10 Fukuoka city tour

Thanks & regards
Linda Khor

Fukuoka to Mt Aso ( by train, bus) and over night at Yufuin. Is one day enough in Mt. Aso?

It is possible, but a lot of time spent on trains and buses. Considering that you plan to visit Kuju the next day, I recommend to spend the night around Aso (e.g. Kurokawa Onsen) before traveling to Yufuin via Kuju the next day.

Is one day enough to cover both view point from Makinoto Pass and Chojabaru Visitor Center?

Yes, more than enough.

Any nearby train go to Kuji mountain?

No.

(should we visit the 1st of Nagasaki kunchi festival?

Any of the three days should be fine:
http://www.japan-guide.com/e/e4411.html

Uji, thanks for your advise. By the way any bus from Mt Also to Kurokawa Onsen?Is Chojabaru Visitor Center near to Kurokawa? We plan for 5 to 7 hours hikeing from Makinoto pass and following by Chojabaru Visitor Center and travel to Yufuin.

I'd say you could see Aso in a day, but please remember it is never assured of seeing it at all
as far as the crater goes - if the wind and poison gas start coming in your direction, you won't see anything. It is a bit of a roll of the dice.
Yufuin is very tranquil and quiet - or dull and boring, depending on your personality. Beppu overall has a better onsen experience. The Hells Tour is nice though and you can get through it in less than 3 hours at a leisurely pace. You can see a good preview of it at
http://www.youtube.com/watch?v=K2NNi8MLcXM
Don't miss the Takasakiyama Monkey Park and aquarium also. It is not expensive and well worth it also. See:
http://www.youtube.com/watch?v=zepPfkuqhok
If you have time and the weather is good, the view from Mt. Tsurumi is wonderful as well
(but not available at night most of the year).
Mt. Inasa in Nagasaki actually is much better,
but worth it if you feel like it.
Nagasaki is a delightful city. If you have 3 hours, be sure to also see Gunkanjima - really nothing else like it without a major dose of radiation in you. See:
http://www.ngs-kenkanren.com/eng/
http://www.at-nagasaki.jp/yakei/en/index.php
http://www.at-nagasaki.jp/foreign/english/
Finally, Fukuoka is a very nice an open city to enjoy, with many beautiful parks. See
http://www.tinyurl.com/see-fukuoka
for some ideas and cheaper places to stay.