You can only use one weapon at a time, but you can kick and use bombs,traps and other tools at anytime during the offline, online or Island quests.
What sort of game is it? In my opinion its a brawler, with strategic elements. You just need to keep working away at each little accomplishment. Start building a High Water Resistance Armor, because you will need it to kill the second large monster (Royal Ludroth). Remember his WEAKNESS is FIRE, so any weapon, or upgrade, that gives you extra fire bonus will take more damage.
The opposite is true for Qurepeco (quite obvious since he/she uses fire as a weapon). So Water weapon, Fire Defense Armor.
Thats pretty much the basics. Everything else you slowly learn, apart from the bleedingly obvious things (mixing ingredients in order to go into a fight with 10 Mega Potions, please!!!).
“When we make some new announcement and if there is no positive initial reaction from the market, I try to think of it as a good sign because that can be interpreted as people reacting to something groundbreaking. ...if the employees were always minding themselves to do whatever the market is requiring at any moment, and if they were always focusing on something we can sell right now for the short term, it would be very limiting. We are trying to think outside the box.” - Satoru Iwata - This is why corporate multinationals will never truly understand, or risk doing, what Nintendo does.
