1) that is just stupid, and honestly a waste to golf. Walking a golf course is an experience upon it self. Golf was made to be walked. It doesn't hurt golf times at all.
2) Plastic spikes can tear up a green just as well as metal spikes. Its how people walk that matter. Fixing spike marks doesn't slow down play that often. Its illegal to do anyways ;)
3) Actually that will slow down play. If I had 1/2 the clubs, i would be sitting there trying to envision what shot i need, and how to play it. Instead of having all my clubs were I would just pull a stock shot 99% of the time.
4) Nope, people will still look for them. I've seen people look for minutes for a pinnacle. Also, how am I going to collect my Pro-V's...
5) Yes, better play can speed up play, but there are plenty of good players who play slow, and have nothing to do with the previous 4 things you mentioned.
If you want to speed up play. Everybody looks out for everybody's tee shots. Everybody plays ready golf. Meaning your picking your club while others hit, and your reading your putts while others are putting. It optimizes time. Finally get rangers to do there job, keep play going. Fastest round is the slowest group, its basic concept around anything in a queue. Golf course is one big Queue.