It's not even a price cut. It's just a discounted sale which is only good for two days. Amazon is currently having a large DD sale so it could be related to that. The standard edition retail copy on Amazon was discounted to around $39.99 a while ago, but they are probably looking to unload any retail boxes left over, especially with Atari's recent financial issues.
F2P? Not a chance. Now is the time to jump in. The game isn't likely to get another discount this low for some time. At about $25 with 30 days included, you're not going to get a much better deal than that, even if you decide to unsubscribe after the free trial. The community is very strong right now and if you are interested in PVP, those servers seem to be the most densely populated (players are more spread out due to PVE server numbers). If you decide to go PVE, join Dragonfall as there are a lot of gaffers there currently.
There is still an over abundance of quests but it definitely takes longer to level from 50-60. You may need to do a little zone exploring as not all the zone quests are in areas where story quests take place. I hit 60 tonight and had a metric ton of quests that I have yet to complete worth tons of experience. Also, the story quests give you insane amounts of experience at that level. It will take longer but it shouldn't feel grindy, especially in comparison to other MMOs. It will go much faster if you find someone to group with.
As Paprika said, everything starts to even out around 55, since you are getting close to cap. This is a good thing in my opinion. This was probably the first time I wasn't able to run around one-shotting everything due to being over-leveled so much.
Pretty much. I think the gear disparity is even worse. Even at level 59 or level 60, I still get wiped by anyone fully geared with tier 9+ equipment. I don't stand a chance.