Yes

A theme or color set consists of any 5 stamps in your album that represent all 5 of the possible themes or colors.

Some contest cards reward you for your 2nd most abundant color or theme. To score these contests, count the number of stamps you have for each color or theme. Ignore the largest number and score the largest remaining number. Stamps do not need to be connected to count for these contests. If two objectives are tied for most abundant, treat one of those as the 2nd most abundant and score it.

Yes

Whenever a specialist card allows you to draw and reserve a stamp, if the stamp is revealed to be rare, you may still reserve it.

When an effect allows you to view a face-down component, do not show it to other players, and return it face down to its original location. When directed to reveal a component, ensure it is face up so everyone can see it.

Yes

Specialist cards are active immediately when selected and for as long as they are in your play area.

The 6 slots in the Daily Collection area of your player mat are numbered solely to remind you that you are gaining a total of 6 items during the Collect phase (the order does not matter).

A stamp is surrounded if it has no empty spaces along its exposed edges (the edge of the player mat counts towards surrounding a stamp).

A group of stamps is a cluster of one or more stamps that are connected along an edge or part of an edge to another stamp in the same connected group.

In the US, a forever stamp is a stamp that holds its value forever; if an envelope needs 1 stamp, I can use a forever stamp I bought 10 years ago on the envelope. In Stamp Swap, a forever stamp is a single square–helping you fill hard-to-reach areas of your player mat–and you will compare your total forever stamps to other players at the end of the game for variable scoring.

A perfect corner is a point in your album where 4 stamps meet at a corner.

Your album has four edges. Each edge is complete when all 12 of the spaces along it are covered by a stamp.

An empty region in your album is a connected cluster of one or more uncovered spaces surrounded by stamps and/or album edges. 1x1 and 1x2 holes are empty regions consisting of exactly one and two spaces respectively.

An empty region in your album is a connected cluster of one or more uncovered spaces surrounded by stamps and/or album edges. 1x1 and 1x2 holes are empty regions consisting of exactly one and two spaces respectively.