Land rezoned to B4 Mixed Use. Interested buyers. How to sell?

We have been lucky enough to be sitting on a piece of land which is in the process of being re-zoned to B4 Mixed Use (as I understand this is high density residential with shops underneath). It is a corner block with lots of street frontage.

Because of this we are now starting to receive phone calls and visits with offers to buy. There's at least two buyers interested in this land and adjacent blocks. We are prepared to sell at the right price.

As this is not one of the usual real estate transactions (that I'm aware of), I was hoping SS could help me with a few questions:
1. How to know what a fair price would be? How would we know what the bump up in price between the old zoning and the new? If I get a valuation done would they take this in to account?

2. How to make the most of the fact that there are two interested buyers? Should I look at using a local agent or would that just be giving them free commission? Do agents need to specialise at this type of sale?

3. What are fair conditions for a contract of this sort? What I understand is it would be a Call Option agreement where the developer only puts a deposit in 18-24 months after contract exchange and settlement would then follow six weeks after. The call option fee is the only money being exchanged up front. As we would like to negotiate both the price and the terms, would my solicitor handle both of these or just the terms?

Thanks again SS, you are a great wealth of information! :)
Where abouts in Sydney is this? I would look at getting the right agent to ensure you maximise what you can get!

Read a story on a sale in Western Sydney where the seller got 1.85m when their neighbour who sold in the same month got 1.2m. The difference was the agents used.
Get yourself together with the neighbours and appoint a valuer to determine what it's worth to each party.

Then negotiate as a bloc not as individuals. The valuer would give you ranges for what each should get from the transaction.

There are several threads on similar topics.

I wouldn't necessarily use a solicitor to negotiate the commercials of the deal as you want them to remain as focused as possible.
I've recently had the fortune of going through this myself. B4 zoned land (confirmed) in Outer Western Sydney. I would think it might be in your best interest to hold out until the B4 zoning is fully approved by council. I found there to be a $200k+ difference in price when this happened, although the Sydney market was also moving significantly during this time.

If you want more details, PM me.