#1 for your first question use a common rule that after you think of your move, check again to look for obvious blunders. Second question, no idea.
Blunders and end games?

[Event "Live Chess"]
[Site "Chess.com"]
[Date "2018.09.02"]
[White "Lordillidan"]
[Black "Hikaru"]
[Result "0-1"]
[ECO "C65"]
[WhiteElo "2860"]
[BlackElo "3057"]
[TimeControl "180"]
[EndTime "12:49:18 PDT"]
[Termination "Hikaru won by resignation"]
[CurrentPosition "r3rbk1/5pp1/2q2n1p/2p1N3/4P3/1nPPB1NP/5PP1/R2R2K1 w - - 0 24"]
1.e4 {[%clk 0:02:59]} e5 {[%clk 0:02:59]} 2.Nf3 {[%clk 0:02:58]} Nc6 {[%clk 0:02:59]} 3.Bb5 {[%clk 0:02:58]} Nf6 {[%clk 0:02:59]} 4.d3 {[%clk 0:02:57]} Bc5 {[%clk 0:02:57]} 5.c3 {[%clk 0:02:57]} O-O {[%clk 0:02:56]} 6.O-O {[%clk 0:02:56]} Re8 {[%clk 0:02:56]} 7.h3 {[%clk 0:02:54]} a6 {[%clk 0:02:55]} 8.Ba4 {[%clk 0:02:53]} d5 {[%clk 0:02:54]} 9.Nbd2 {[%clk 0:02:51]} h6 {[%clk 0:02:53]} 10.Re1 {[%clk 0:02:50]} b5 {[%clk 0:02:51]} 11.Bb3 {[%clk 0:02:48]} d4 {[%clk 0:02:51]} 12.Nf1 {[%clk 0:02:43]} Be6 {[%clk 0:02:49]} 13.Ng3 {[%clk 0:02:38]} Bxb3 {[%clk 0:02:43]} 14.axb3 {[%clk 0:02:38]} Qd7 {[%clk 0:02:40]} 15.b4 {[%clk 0:02:24]} Bf8 {[%clk 0:02:37]} 16.Qe2 {[%clk 0:02:22]} dxc3 {[%clk 0:02:22]} 17.bxc3 {[%clk 0:02:20]} a5 {[%clk 0:02:20]} 18.bxa5 {[%clk 0:02:16]} Nxa5 {[%clk 0:02:20]} 19.Be3 {[%clk 0:02:11]} c5 {[%clk 0:02:17]} 20.Red1 {[%clk 0:02:06]} Qc6 {[%clk 0:02:08]} 21.Qc2 {[%clk 0:01:45]} b4 {[%clk 0:02:02]} 22.Nxe5 {[%clk 0:01:30]} b3 {[%clk 0:01:53]} 23.Qxb3 {[%clk 0:01:03]} Nxb3 {[%clk 0:01:49]} 0-1
So I've got two questions.
1. What's the best way to stop blundering during 30+0 games even after spending time looking at each move.
2. What's the best way to study and practice end games?