It is very difficult to determine value without actually being able to examine stamps. There are catalogs online that can help identify the stamps and provide a general value. Condition is important to determining value. And the actual value is not necessarily what is in the catalog. Most dealers will pay about 25% of the catalog value, particularly for low value items. If it is a high value item, you may be able to get more for it.
Online sites that have stamp value guides include Stamp Collecting Resources, Stamps Site UK, Hobbizine, Find Your Stamps Value, Stamp Treasures and Mystic Stamp.
There are some online stamp catalogs available. I often use the one by Mystic Stamps. They have put their paper catalog online and it includes information on how to determine condition. The values provide are those at which they are willing to sell the stamp. Buying will be a fraction of that value.
There are a number of online stamp catalogs available, some do charge a fee. Others have a catalog with prices to purchase stamps from them, but it can give you and idea of value.
"A " stamps are the same as 15-cent stamps.
There are a dozens of stamps issued in the 1980s. You will have to consult an online catalog for information to figure out which one you have. That will provide you an estimate on the value.
Most stamps will show the value of the stamp somewhere on the design.
Barely, probably the face value of the stamp.
You can consult a stamp dealer in your area. A knowledgeable collector can probably help you with their references. You can also do it yourself with a stamp catalog either online or at your library.
The G stamp has a face value of 32 cents. The H stamp has a face value of 33 cents.
This is a very admirable hobby to get into as millions do in the US. You can get some ideas of value at values.hobbizine.com/stamps/index.html.
Stamps that are not used are referred to as 'mint' stamps. The actual value will depend on the condition and the specific stamp. Consult a catalog to determine the value of any stamps you have.
Value entirely depends on what stamps are in the album. Without knowing what stamps, country and condition, it's impossible to value.