5 or 6 Days Winter Hokkaido

Hi,
For someone from a tropical country im really keen on experiencing snow and i believe hokkaido is the best destination to visit for both experiencing the snow and nature. Im still on the planning stage so heres my initial list im interested in.
1. Sapporo
2. Otaru (maybe half day)
3. Ski at Niseko (2 days 1 night)
4. Biei (im not sure if its still magnificent at winter since blue color might be block)
5. Snowshoeing
6. Onsen
7. Drift Ice (if possible)
8. Nature (Mountain, Beautiful Nature Scenery)

Day 1
(Manila to Sapporo)
- Nothing to do here, at most it would be just couple of hours if the event we arrive at destination

Day 2
- Sapporo City

Day 3
- Biei (If possible with either Furano or Ashikawa)

Day 4
- Niseko
- Ski and Other Winter activities

Day 5
- Niseko to Otaru
- Half Day Otaru before late afternoon flight out

Im willing to extend my days but i guess the minimum possible days is 5 as of the moment.
Those that are in itinerary are the ones i guess are a must visit for first timers.

- Does my itinerary looked abit tight?
- Is half day enough for otaru since i believe the main sight is the canal.
- Is biei still beautiful in winter?
- Is it worth the trip to go all the way from sapporo to niseko for an overnight? or are there ones near sapporo that is equally good?
- Any place that i could experience good onsen thats near the ones on my list? and also snow shoeing, that would be exciting?
- I guess accompanying elderly on this trip i couldnt afford to go all the way up to shiretoko for a good nature trip. Is there anywhere near central hokkaido that is as good as shiretoko in winter?

Thank You

Biei is especially beautiful in winter in the snow and there is much more to see than just the Blue Pond. But even the Blue Pond in winter is great and very busy with visitors, especially at night when it is lit up which is a few nights every week:

http://monochrome.me.uk/blog/copse-biei-hokkaido-1/
http://monochrome.me.uk/blog/aoi-ike-blue-pond-frozen-over-1/

As for onsen recommendations, up the road from the Blue Pond in Biei is Shirogane Onsen with some decent hotels and great baths and the road stays open in winter, there is also the Shirahige waterfall which is mostly frozen in winter.

http://monochrome.me.uk/blog/shirohige-waterfall-shirogane-onsen-1/