For instance I want to suggest a spell or a generic action to an ally because my PC has a better view of the battlefield. Can I do that or I must wait my turn?
One thing my last DM did that helped at high levels (also low levels, but especially high) was to split solos into, effectively, three monsters. So a dragon might become the head, the body, and the tail; while a demon might be head, body, and arms, depending on the powers. He would divide the solo's actions up and give each piece hitpoints so that two of the pieces were equivalent to an elite monster and the third was equivalent to a standard monster. Each piece gets its own initiative and set of standard/move/minor actions, and players target pieces separately (so, for example, an assassin could shroud the head, but wouldn't get shroud damage if he then attacked the body).
You would want to adjust the specific mechanics for your own game - we tended to address issues like whether "slowed" affects one piece or the whole creature on the spot and depending on how the creature was split up - but if your aim is to reduce complexity, it would be worth figuring out satisfactory answers to common effects up front. Then once play starts you already know the answer.
It ends up being significantly simpler for the DM since you have the strength and threat of three monsters, but the abilities and powers of only one to keep track of. It also requires fewer additional monsters/terrain/whatever to build out the encounter, again reducing the complexity of any given combat. You also get the advantage that a combat against a solo becomes much more interesting, because you've got three parts of the monster moving and acting independently (preventing the solo from being pinned down and focus-fired), which again increases the fun without increasing complexity.
On your turn, you can move and perform an action. The ready action is, as you point out, an action like any other. This means that on your turn you can move and take the ready action.
The Ready Action
The ready action allows you to react to a specific, "perceivable circumstance."
To do so, you can take the Ready action on your turn so that you can act later in the round using your reaction.
When the trigger occurs, you can either take your reaction right after the trigger finishes or ignore the trigger.
Remember that "[a] reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's," (Reactions), meaning it happens immediately after the trigger occurs.
However can you move on the same turn that you ready an action?
Yes, you can. It is an action just like any other, and is taken on your turn.
Secondly when the trigger goes off do you have to wait for your turn or do you in effect get a bonus turn?
It's a reaction, and happens immediately. It's not another turn, nor do you have to wait. It happens when the trigger, well, triggers it. Reactions can—and almost always do—occur on someone else's turn.
A few notes on the ready action.
- It takes up your reaction, so you can't perform the readied action and an opportunity attack in the same combat round
- The readied action happens when the trigger occurs, but any movement has to be done on your turn—unless your reaction is to move. It does not move your turn in the initiative order
- Spells used for a readied action gives that spell a concentration requirement, and thus doesn't work if you already are concentrating on a spell (or you could choose to stop concentrating on it)