In reply to VS4b: I work in recruitment and manage all our contractors and contracts - our contracts have passed every independent assessment they've been through re IR35. IR35 can be a bit of a headache, but equally is rarely a problem in practice - it depends how the contract is set out, and whether it is going to be a problem or not really depends on the contract.
Generally speaking, you should be better off with a proper contract (as opposed to an FTC), but only if you have your own limited company instead of an umbrella company - you pay far less in fees, and your accountant may be a bit more creative. My concern would be why they are looking at the two options: FTCs are generally cheaper for the company than a 'proper contractor', and so they might be trying to get you on the cheap (certainly an FTC doesn't look as good on your CV), but conversely if they are trying to make it a contract role and thus to your financial advantage, that would be concerning re IR35.
Ideally, you want the contract to have milestones in terms of work - so that it isn't purely done on dates; you should avoid having a notice period (though if it's going to be a 2 year contract you'd probably want to avoid that!), and make sure it's business contract (so you have professional indemnity insurance requirements etc), and a lack of control, and an unrestricted right to substitution. Ultimately though, it's the whole of the contract and the circumstances around it that will let it pass IR35 or not.