Tier 2 ICT Visa cooling off

Hi Team,

Am currently in UK on Tier2 ICT since 2015 Aug and planning to switch to Tier 4 student Visa in Sep-2020 batch. My current Tier2 ICT visa expires in mid July-2020 as am completing my 5 years tenure in ICT. Have the below queries and could you please clarify me.
1)Can i apply Tier-4 from UK itself without travelling to my home country before July-2020 to stay back in UK.
2)Can i apply to college before July for CAS and am i allowed to submit my Visa application if i get CAS from university by July-2020. this is to have stay continuity?
3)Am i eligible for PSW visa once i complete my course or do i need to face any issue with my ICT tier2 cooling off period as i haven't served my ICT 12 months cooling off period.
4)Can i switch to Tier 1 in middle if UK introduces points based system , I have 15 years of IT experience.so can i ignore my Tier 4 visa once UK introduce points based system to apply Tier1 visa?
5)to Get ILR do i have to consider any key point while switching the Visa. i mean submitting T4 application before my T2 visa expiry.

Many thanks in anticipation.