Steils

Pennies are fine, the join-tite will seal it from water getting in. We use lead personally though. The problem with vinyl is that in the rare case that water gets in it can cause the stone to slide. Though we don't see that often but have done a few repair jobs where this was the case.

Where I work, we either use the crane on our truck if we can get close enough, if not we set it with a 4 wheel cart that transports the base with the headstone on it by using two chains under it that lift it just high enough. Then we set it down on top of the foundation onto plastic strips and lower with a pry bar right onto the setting compound.

Most anything you buy today will last pretty much forever if not destroyed by someone, like hit with a car, lawn mower, or any thing like that. Todays headstones are made from Granite(almost all) which is about the strongest rock you can get. As long as you get good quality Granite that is.

A lot of smaller companies sell China Granite as it's cheap and helps them get the sale for price shoppers. Most people going to buy think all Granite is created equal. Not true, there are thousands of quarry's around the world to get it from. The Granite from China, mostly Gray and Black is not very good. It has Iron in the stone which will, over time, absorb water and rust which can cause your stone to crack and get pits or discolor. Also the Black granite from China is not very black, so to get it to match competitors darkness they will add a black die to the granite which will wear out, as we've see in as little as 2 years, creating lighter spots on the stone.

Here are 3 images of this, 1. Gray Discolor 2. Black Die Coming out 3. Rust http://imgur.com/a/w45NC

You can do pretty much anything as long as they follow the rules of the cemetery. Almost all require Granite Headstones as they are what last. Marble/concrete/limestone don't weather well over time and will eventually fall apart. The only marble ones normally allowed are the ones that Veterans can get for free from the VA, almost all get the bronze though.

The most common things allowed to be added to the headstone that is not directly etched into the granite is: Porcelain, Bronze, stainless steel. As for adding LED's you must think, this is going to be outside in the hot/cold/rain and will not weather well, also you'd need a small solar panel, which would be costly to get a good one(someone may steal it). The cheap ones that people use for things like candles can get water in them, then the water will freeze breaking it. Mostly it's best to only put up what will weather well, and last.

I work with quite a few granite companies and engravers, also engrave myself. We throw around ideas and think about what we want all the time. Though in 13 years in the business I've only ever known of one person, who did a lot of our sandblasting, to buy a stone. That was shortly after he retired. He did not engrave it himself and had us do it. So to answer your question, probably around retirement age.