You can only be granted permission under the Graduate Route once in your lifetime; think carefully about whether now is the right time for you to apply.
Research the job market in your industry; plan ahead and make sure you can support yourself if you don’t get a job straight away; you will still have the “no access to public funds” condition on your visa.
You should not leave the UK while your application is still pending; this will automatically withdraw your application.
Once you have been granted permission under the Graduate Route, there are no travel restrictions.
There is no choice about the length of your GR permission; if you are a PhD student who only wants the visa for 2 years, you will still have to pay for all 3.
You can’t extend your stay under the Graduate Route, but you can switch into several other visa categories if you meet the requirements of those visas.
Permission under the Graduate route does not lead to settlement.