Napoleon almost always attacked. He was a great believer in the attacker's power to decide the time, place, and other circumstances of battle. The defender must accept battle on the attacker's terms. Napoleon always prefered to control the battle through the use of offensive action. For Napoleon to surrender the initiative and let Wellington attack him would have been out of character. It also would have allowed Wellington to wait for Blucher to reinforce him.
Because that's what he did. He was the agressor, the invader. That's why Wellington had marked the site long before. He knew he'd be fighting a defensive battle against a French attack. He didn't know the Prussians would be defeated when he planned it.
Agreed. Here is a website that has some of Napoleon's quotes on Warfare: The Words of Napoleon and Others Who May Have Influenced His Methods
It is very noticeable how strong an emphasis he puts on aggression and offense.
This too. Like Chlodio said in the above, if Napoleon waited, he would simply give Wellington & Blucher more time to combine. Even if he would be convinced that Blucher would have been thoroughly routed, Wellington might adopt more Fabian tactics against him, and hence drag the final decision out. It was a gamble, but had Napoleon succeeded in crushing Wellington and then finished Blucher off, he might have held onto the hope of shattering the resolve of the Alliance and pave way to a negotiated settlement for his return on the French throne. Other threads have already mentioned why this is a very unlikely outcome, with the Russians and the Austrians massing their armies, and Napoleon's promises of peace ringing hollow. After all, he already returned from Elba. Who is to say what he would do in another ten years after raising a new Grande Armee, if he was left in control of France?If you have space and time on your side that's fine.
Above all he was running out of time.