First off let me welcome you to the forum's.
Second let me a sure you that Necrons can still be quite good and even competitive if used well. To prove this, I encourage you to go to the Batrep section and cheack out a few of the more recent (2008+) threads that have Necrons featured in them. I took the time to assemble a few together for you (and I can get you more) but these few are just from my own us of the Necrons in 5th ED.
1000pts of TMGM vs SM's 10 Dec 2008
1000pts of TMGM vs SM's 19 Dec 2008
1500pts of TMGM vs Orkz 29 Jan 2009
1000pts of TMGM vs Shirke SM's 17 Feb 2009
1700pts of TMGM vs New IG 22 Apr 2009
1700pts of TMGM vs Space Wolves 31 Aug 2010
As you can see I actually do see a number of different opponents and so far I have not been Phased Out in 5th Ed, and The Mighty Green Machine is actually winning way more games than they lose. This is not because I am so great, By the Way, TMGM is winning games because the Necrons are often under-estimated. Thus you need to familiarize yourself with some of the more underhanded tactics of the Most 3vil race in 40K. If you look in my signature (below) you will see a link to the Guide on Necrons, and there is a host of great info in there that I assembled from many many great Necron Generals. It is also filled with links to more Batreps, guides on how to convert Necron stuff to be even cheaper on your wallet, tactica's, ideas on army usage, etc.
To answer your questions directly.
~~ Jaws is based on the init of each figure it contacts, so your deployment and subsequent movement can actually limit the effect of Jaws to fewer or more figures being effected.
~~ Living Lightning is a gimick if you ask me as he might roll a 1 to only even have 1 chance to effect anything (6's are not so good for the Necrons) but you still get all of your saves, and your WBB's if appropriate.
~~ Lash can be gross if you allow that guy to get close enough to cast it, etc. But tis near useless on things like the Monolith and the Mono can be used to Block Line Of Sight (BLOS) etc. The Lash is also often carried by an independant figure, so some strategic shooting can remove that figure before the Lash is ever an issue. Daemon Princes don't do so well vs mass Destroyer Fire, etc.
~~ Deepstrike is not reserved for Monolith's only, Flayed Ones and some other Necron units can also Deepstirke, so I serioulsy suggest that you invest some time into learning when and when not to use it, and how it can be used more effectively.
I personnally don't find that I need Monolith's all that much in 5th Ed (although I certainly know how to use them - and they are great). the one factor that I feel every Necron army needs in order to survive in games in 5th Ed though is "Shock Absorbers" and fortunately those are abundant enough in the Necran arsenal. Pariah, Scarabs, Tomb Spiders, Monoliths, etc, etc can all be used as Shock Absorbers to pruchase your Warriors a better chance to score/survive a battle.
Feel free to ask me any questions you have or to clarify anything I offered you so far, and once again welcome to the Forums.
PS... Welcome to the "Tomb World" and just remember this for whenever you begin a battle; "may the best
man Machine win"
Cheers