STD. AMERICAN - 2 over 1, Bidding with a 5 card major and 16 points
This is a matter of partnership agreement. In particular, it is reasonable either to almost always or almost never open 1NT with a 5-card major.

If you are in the almost always camp, assuming a 15-17 NT opener, you should open any 5332 hand with a 5-card major and 15-16 HCP 1NT unless all of your points are in your major and one of the side suits. These bidders will also likely open 1NT with the appropriate point count and semibalanced shapes that are difficult to rebid (e.g. 2=4=5=2, 2=4=2=5, but not 4=2=5=2 since you can raise or introduce spades without reversing). Puppet Stayman is not a necessity, but it is useful. Justin Lall has a useful post about Puppet Stayman.

If you are in the almost never camp, you should open those hands one of the major. The types of hands that would open 1NT with a 5-card major would be those that have positional stoppers or half-stoppers in 2 or 3 of the side suits (like QTx, Kx, Qx) along with a poor 5-card major.

The most important thing is to be on the same page as your partner.

As to how to rebid after opening 1 of a major with a semibalanced or balanced 15-17, here's a guide:


If you have a 4-card suit lower than the suit you opened, rebid that.
If your shape is 4=5=2=2, rebid 2C.
Otherwise, rebid your longer minor at the two-level, preferring to bid a 3-card club suit before a 3-card diamond suit. However, be sure to discuss this with your partner -- you may find that you both prefer to rebid 2D with something like xx AKJxx AKx xxx.


Obviously, if partner invites, you'll accept. If partner takes a simple preference to your first major, you will probably want to make a game try:


If you have 3-card support for partner's suit, bid it as cheaply as possible.
If you have a truly excellent 5-card major (AKJTx or better) and values that look better for a suit contract than NT (fitting honors for partner's suit, side suits with either no honors or with quick tricks), you might make a try by rebidding 3 of your major.
Otherwise, 2NT.