Do we have to pay the freeholders costs (we do when re doing a flat lease) Currently,
For Sec 5 (right of first refusal) No (unless it says otherwise in the offer), for collective enfranchisement, yes. But that is changing. If you accept the offer and withdraw, i.e. your bid collapses, you will be liable for costs.
Can we charge what ever we want for lease extensions when we buy the freehold or do have to still abide by the current formula?
You can offer a better deal, but you cannot offer a worse deal
What is the formula for buying the freehold and is £60k a correct price or should we negotiate?
You haven't shared the details of all the leases, so nobody can help with the calculations..
might help you get a rough idea for each lease.
If someone else buys it what is the impact on us? For instance can they demand we pay any amount for renovations like roof etc?
No and the direction of travel is that freeholder/landlord are going to be more and more restricted.
Almost everything to do with a Lease/freeholder dispute can be settled via tribunal. (a form of legal arbitration). But currently Freeholders rely on the leaseholder not wanting the hassle.
So rogue agents tend to add a £100, here £50 there in the hope you wont take them to the tribunal. Building insurance is the biggest con as they get kickbacks of around 50%
