六月同媽和仔去北海道 Itin 和 Driving. Please help!

淺笑梨渦
請大家給意見. I am going to Hokkaido with mom, younger sister and my son (8 years old) this coming June. Preliminary, I've come up with the itin below. But I have several questions:

Draft Itinerary

day 1: Hk - Sapporo. sleep in Sapporo
day 2: otaru day trip. sleep in Sapporo
day 3: Sapporo. sleep in Sapporo
day 4: Jr to 旭川. pick up car and drive to zoo. visit 青池。sleep in 美瑛
day 5: drive around furano area. sleep in 中富良野 or富良野.
day 6: drive to visit 富良野 in the morning. return car in 富良野. take afternoon Jr back to Sapporo. sleep in Sapporo.
day 7: last day shopping in Sapporo. sleep in Sapporo.
day 8: take afternoon flight to HK.

Questions

1. I'm also considering should I do 富良野 area first on day 2 to stay for 2 overnights , and then return to Sapporo on day 4. Then this will leave us a total of 3 days in Sapporo to do one day trip in Otaru, and perhaps 1 day in 登別 more conveniently.

2. 1st night stay in 美瑛. Then 2nd night should stay in 上富良野 , 中富良野 or 富良野? Where is more convenient to stay for the sake of sightseeing the major attractions?

3. How closes are sightseeing places in Sapporo city? Can do most by metro + on foot? Or I should consider to rent a car starting Sapporo and then after returning from 富良野, continue to rent the car to visit Sapporo? What I am concerning is:

a) Is the drive too long from Sapporo to 旭川 zoo, back from 富良野 to Sapporo? Only myself will drive. Any good stopover in the mid way to rest?

b) How's the driving condition in Sapporo? Traffic congestion a lot? Difficult to find parking in sapporo?

4. Worth to visit 登別 for 1 day for onsen?

Hope someone can help me plan.

Many many Thanks
嘟著小嘴耍任性
1. 要去登別, 札幌就減少一點吧
day2上午札幌, 下午往登別
day3登別回, 下午逛小樽
2. 有租車, 住哪差不多, 不過6月可能花還不多, 可多逛逛美瑛
3. 若主要是逛街跟市中心景點, 札幌不用租車, 若不考慮JR費用可能較多, 在美瑛富良野區域租車就行了,
要從札幌開始租車的話距離也還好, 走高速或國道中途都有休息站
4. 若想泡溫泉, 去登別當然不錯
你長了一張欠吻的嘴
1. 要去登別, 札幌就減少一點吧
day2上午札幌, 下午往登別
day3登別回, 下午逛小樽
2. 有租車, 住哪差不多, 不過6月可能花還不多, 可多逛逛美瑛
3. 若主要是逛街跟市中心景點, 札幌不用租車, 若不考慮JR費用可能較多, 在美瑛富良野區域租車就行了,
要從札幌開始租車的話距離也還好, 走高速或國道中途都有休息站
4. 若想泡溫泉, 去登別當然不錯

Thank you. I am likely to drive only in Furano area. I am planning to stay a night in a hotel with onsen facility in Furano area.