You can use a tile map to design your levels. Tiled is what I use. Works well. You just need to load that data into an array. You can also just design your levels in code... visually an easy way is to just use lines of strings then parse and convert to integer image references. There is also the GUI-based Placement Editor which although I have never used it should also work for this. Of course, you can also build a very simplistic level editor. Doesn't need bells n whistles just something to let you visually select tiles, place them and save & load that data. Basically there are many options. You choose which is right for you. I think building a simple 2D map / level editor would help you a lot to not only create a tool you can change whenever you need to but also to learn AppGameKit programming.
It's not objects that let Unity do this for you it is the entire framework and model of using component based design. Their internal code calls update on every gameobject. AppGameKit doesn't use that component-based model. Again you can do it however you want here. If you want to do it in a more object oriented way just make a file block.agc that has only the variables and code to manage a single block. Use a TBlock type to define the data properties for a block. Create another file BlockManager.agc or LevelManager.agc whatever and declare an array of the TBlock types. This Block Manager is your main interface in to working with the blocks and will call the functions for an individual block that you write in the Block.agc file. Personally I see that as just an unnecessary level of abstraction and would have the BlocksManager do all of the work right there.
For collisions again you can write a BlockCheckCollision function passing in the spriteid of the ball and then just loop through the array of TBlocks and use GetSpriteCollision api function. More commonly you can just check the map data (from your tile map level editor data) for a collision. Again you can do it however you want to. You have a ton of freedom with AGK.
