You can get free diamonds, iron, rare blocks, etc. by going into creative mode and placing all the blocks you need, then go in to survival and dig up the blocks you placed! You will get the blocks free!
If you want the house to be strong you should dig deep underground and find rock or other hard substances that there are a lot of. Make sure you are able to get back above ground. Once you have enough go back up and start building. The best size is probably a 10 by 10 or bigger if you want. If you want to be really fancy you can also slap some wooden flooring to the house. Do Not Be Afraid To Double Up Doors Or Walls For Extra Protection Against the Things That Can Hurt You. I hope that my knowledge of Survivalcraft could help.
If you don't know how to do something, press the 3 dots in thetop right corner of the screen. Then press the question mark. You will see alot of tittles of actions you can do. In green in the bottom right you'll see something that says recipia. Press it and look for the block you want to do and then press recepie in the corner. Note: somethings don't have recepies because they can't be made.
Start a new world and put it on creative.there you put a chest in front of you. Place anything you want in the four box ( diamon spears or anything) put it in the chest quit the game and go to the modify screen. Change your creative to the mode you want. Come back to you game and your item will still be in the chest. Hope this help starter create they first world.
First go on creative mode then get a chest then place all the diamonds and free stuff you want in it and go out to survival mode and open the chest.
Animals CAN step on pressure plates and trigger them. I don't know the specifics, but I figured this out because an angry bull followed me and triggered the pressure plate opening my door. Another thing too: Almost all animals are not capable of going through a 1x2 door.