Section 107 of Transfer of Property Act specifically provides that a lease of immovable property from year to year, or for any term exceeding one year or reserving a yearly rent, can be made only by a registered instrument.So the answer of first two queries is that for the lease deed of 3 years of more,it has to be registered.1.Jagjit Cotton Textiles Ltd. vs A.K. Malhotra decided on 1 September, 1995
For the answer of your third query,two cases are interesting,
2.Sumikin Bussan (Hong Kong) International Limited vs Manharlal Trikamdas Mody And Ing Bank, N.V. decided bon 2/5/2006
In first case issue was raised whether an agreement was lease or license.
In second case, whether agreement of license was revocable or not.
Mere use of the words appropriate to the creation of a lease will not preclude the agreement operates as a license. A recital that the agreement does not create a tenancy is also not decisive. The crucial test in each case is whether the instrument is intended to create or not to create an interest in the property the subject matter of the agreement. If it is in fact intended to create an interest in the property it is a lease, if it does not, it is a license.To put it precisely if an interest in immovable property entitling the transferee to enjoyment was created, it was a lease; if permission to use land without exclusive possession was alone granted, a license was the legal result.
In the second case the court goes on to say that It is no doubt true that Section 60 of Easement Act mentions only two classes of cases in which the licence could be regarded as irrevocable. This means that where a case falls in either of these categories the licence is made irrevocable by operation of law, that is the Easements Act. But apart from the Easements Act, there is the law of contract and if parties enter into a contract and arrive at a solemn agreement to the effect that the licence shall be irrevocable or shall be limited for a particular duration, it follows that the licensor will be bound by his engagement and will not be entitled to terminate the licence or revoke the licence at his sweet will and pleasure.
In one another similar case The Division Bench of Gujrat High Court held that even if there was such an agreement, the licence would be revocable at the will of the licensor. Referring to Section 64 of The Indian Easements Act, the Division Bench held that the provisions of Section 64 which entitle a licensee to recover compensation from the licensor for wrongful eviction, indicate that compensation is the only remedy of the aggrieved licensee. The Division Bench held that even if there is such an agreement and the licensor evicts the licensee before the term of the agreement has expired, the only right the licensee would have, is to recover compensation from the licensor.
The similar decision was givenby Supreme Court in Re Ram Saran Gupta where the Court asserted the license revocable irrespective of the agreement in writing. The difficulty arises for the licesee to continue in the promises and recovery of the security deposit after sale of the property by tranferor as transferee has no obligation to oblige the license agreement, as held by Honourable Court time to time.Even after hard fought litigation,the security deposit may be recovered, it is quite not possible to continue tenancy, as deep understanding of the subject says.
Therefore I am of the opinion that lease agreement is mush suited in your case as property cost might be high and lease makes chunk of your company's business.