What's the problem here? In your example game you crush an opponent rated over 100 points above you. It's black who should be looking for improvements. 8... Ne5?! especially when combined with 10...c5? looks really questionable to me.
Ideas in the Philidor

I agree with shakaali. I think Black needs improvement. I don't play that kind of Philidor. I prefer the Hanham Variation of the Philidor's Defense. Some people call it the Lion's Claw but I don't know why.

Better for Black would be to maintain the pawn at e5 as long as he can, or at least until he is in position to use one of the above maneuvers to advantage. So more usual would be ...Nf6 or ...Nd7. But even in this case, White should be better by proceeding with natural developing moves - Nf3, Nc3, Bc4, 0-0 can't be bad.
I don't really agree. I happen to believe that 3... exd4 is probably black's best bet (at least in practical play) in the normal Philidor move order. There are certain problems with the continuations where black tries to hold e5. Actually, for this reason the Philidor is nowadays often reached for example via pirc move order which restricts white's options and allows black to keep e5. It's worth mentioning that in the current master practice 3... exd4 is played more often than all the other alternatives combined and in super GM level almost exclusively.
In short, 3... exd4 isn't terrible (altough definitely should be small edge for white with correct play) and isn't so easy to punish imo.
Also, 6. Be2 appears to be the most often played move for white and the average rating of the white players employing this move is higher than after Bc4. Be2 has been played by Anand, Ivanchuck, Grischuk etc. so clearly it can't be that bad.

Is interesting Perplexing (1375) vs. Opponent (1512) looks someway sisilian defence line, when 10...c5. Sicilian exd4 is not bad at all. Yes, little different position minor pieces, but Grand Prix attack (f4) look-alike:) !!

I do not believe this is correct. In my recent games database, 2007-date, mostly TWIC with a few additions, there are more games with both 3...Nd7 and 3 ...Nf6 than 3...exd4, with ...Nf6 15 x more common than ...exd4.
What games do you find at the "super-GM level" with the Philidor, 3 ...exd4 or otherwise?
I have a database containing tournament games from 2003 onward (mostly TWIC, almost up to date) and there 3... exd4 is played over 60% of time (in older games I would expect to see other moves more often). Average rating of black players choosing exd4 is around 2300. Among 2650+ players exd4 is the only move chosen (45 games in all; Nakamura once ventured the ancient 3...f5? but that hardly counts)
I found 20 games where both players have ELO 2650 or more. Admittedly at super GM level this line is mostly seen in rapidplay or even blitz (altough there was also a game played in Corus A among others).
Hello Chess.com community! I have played against the Philidor Defence many times and I keep making horrible blunders simply because I have no attacking plans. My development is good, but for you more experienced players, what would White's general attacking plan be. I can show you a sample game (that I won by luck), that touches base with the simple principles of how I develop. If my development is incorrect please tell me! Thanks!