| Immolate |
Cash is hard to come by and the rulebooks are expensive. But there are ways that don't require the expense. Use the SRD rules if you have laptops or tablets and an internet connection. Ask for books for birthdays or Christmas (or whatever).
This may sound like politically correct platitudes, but diversity in a group is a benefit, though as you've learned, it comes with challenges. Everyone doesn't have to be serious in the game, just serious about the game for it to succeed. I have a group of friends that I've been playing with for 33 years. Some of them are serious role-players, some are competitive, some are jokers, and some are hack-and-slashers. What is important is how the group interacts as a group, as people. If they are compatible as companions, then the rest will work itself out. Do you really think a bunch of forty-something guys have faithfully assembled each week for decades because the game is just that good?
It's good for players to try creative things to overcome challenges, but you have to establish boundaries. Acting upon other creatures and even objects have well-established rules, though you'll always find gaps. If you want to push someone around, you have to bull-rush them, drag them, or some other combat maneuver. Inanimate objects aren't good at combat maneuvers, and magic is less effective than flesh when attempt to accomplish these maneuvers (with certain Bibgy exceptions). Items have hit points and hardness that must be overcome to "break" them. You can't easily overcome the hardness of a stone statue with magic missiles, and if you can, it will probably take a while. Then what are the odds of it falling in the right direction? Any reasonably intelligent creature would notice that you're chipping away at the statue's base and move away from it to avoid being crushed, or throw its weight against it to push it in your direction. Let them be creative, but you be creative too, and make things hard to do, just as they are in real life.
Keep in mind that monsters are typically interested in winning, not just providing a challenge to the party. They will cheat, misdirect and bamboozle just like the party does. Teach your party early on that whatever they bring to the game, the monsters can use as well. Players are always trying to find a rule or a gap in the rules that allows them to have a significant advantage. That's okay if they've invested the feats and skills necessary, but we DM's need them to be as careful a guardian of game balance as we are. We do that by giving them incentive to self-regulate, and by limiting their actions in a reasonable manner.
Example: if someone swings on a rope into the middle of a throng of enemy soldiers, they might find spears set against their charge, they'll be grappled by several soldiers right away, and stabbed repeatedly for their silliness, that is if they don't fail their DC15 climb check and fall flat on their back and render themselves unconscious.
It's hard to know all the tricks starting off, which is why most people play in other DM's campaigns for a while before taking the plunge. But when we started, there were no other DM's, so we had to learn the hard way. It can be done and it's really a ton of fun as well, so just keep at it and you'll be looking back at these times as some of the best some day.