Shates for the poof of work (mining)

Neby questions to litecoin, blockchain, mining (isn’t the mining process the proof of work):

Where to get good and reliable technical details how proof of work works with script algorithmus in the litcoin blockchain?

What helps to decide when to sell the litcoin miner to make cash and keep mined litecoins? We only got one miner yet. Newbys to the materia. How (where) to recap the shares in equition to megahash etc. for powering a mining machine?

Is it also possible to buy the ASIC boards solo and build a miner by its own? Where to look for components to build it?

Dirk

P.S.: Answers links etc. prefered in german language also for my collegue. Not needed for me.