With regard to Point 4.
A plain UK PPL is allowed to fly IMC in Class G so long as two conditions are true
1- they are in sight of the surface
2 - they have 3 km viz
So you are right, they can not be 'in cloud', however, they are not required to comply with the cloud clearance or in flight visibility requirements for VFR operation in Class G above 3000ft or above 10000ft (so long as they follow the IFRs - which at that altitude are only to fly quadrantals), nor are they limited to 140 kts for the low level clear of cloud restriction of VMC because high speed low level flight clear of clouds with at least 800m viz is legal UK IFR and so long as the viz is 3km is legal for a basic PPL.