hi, sorry my article wasn't more helpful. we'll see what we can do
it sounds like you got the previous version of the box (that's fine, they're largely identical)
you're looking at two things (Total Warfare & BattleMech Manual) and a third (Alpha Strike), which is very different.
Total Warfare is the main core rulebook of battletech. it covers a variety of combat units from mechs to infantry to combat vehicles and more. It's set in the universe year 3067 so it has some new equipment, but not all the most bleeding edge experimental gear (Tactical Operations has the extras)
BattleMech Manual is a bit different in that it covers only BattleMechs. This book is set around the universe year 3150 and so includes a number of systems that were considered experimental in 3067, but now are commonplace (like calculators and microwaves in the 70s compared to now). Once again, it includes no rules for units other than mechs. keep in mind that just because they have an in-universe year, you can still play with any equipment you want. you aren't forced to use everything or place your games in a specific time period.
Alpha Strike is a different animal altogether. It presents a streamlined version of the rules (for example, all weapon ranges are standardized to 6 inches, 24 inches, and 42 inches) to be played as a miniatures game on a table with terrain like Warhammer or Warmachine. It plays a lot faster so if you like big battles and units that are eliminated much faster, these are the rules for you.
As to the in-print status, Total Warfare was just re printed this fall and i've seen it on ebay at normal prices recently. The BattleMech Manual was just reprinted and you can order it directly from Catalyst right now (store.catalystgamelabs.com). Alpha strike is currently both out of print and hard to find. there will be a new printing estimated for later this year
hope that's more helpful!