Haha, I did that too, but i modify myself also.

Preferably new tenancy agreement. Unless your old one had a clause "Renewed automatically with same terms and conditions" but you will still need to re stamp if you want to declare.

quite right... for residential, it was commonly 2yr+1yr or 2+2.
but due to many available houses and highrise now for rental, many tenants start to insist on 1+1.
in my experience, most of them get out after 1 yr because they find a better one nearby with same or slight rental incr.
this says the yield for rental props is flat or getting lower as there is ample supply for rental.
there are many cases where a good rental is achieved for 1 yr, then stays empty for 1yr before next tenant comes in.
this is happening in many places. when situation will reverse, nobody knows.

for commerical operations, it is usually longer, maybe 3+1, 3+2, or in the case of banks in shoplots, 3+3+3, total 9 yrs with a provision for a capped rental incr every 3 yrs.
again as previously mentioned, there are no hard and fast rules. both sides need to agree, according to prevailing and anticipated future market conditions.

Are you an agent? If so, I might need your service around summer next year.