keep themselves updated with the
latest advancements in web domain
I think in this very beginning, you should be their tutor and guide them yourself: collect some information about web development, create a schedule and a list with the most important topics you think they have to know. (Look at this thread in SO how many information about a "generic website" is important to know. It's not specific to php, but the security section for example is a must!)
Then, you can create the "tips website" by yourself. Create a blog - from tumblr to wordpress - and each day post something yourself. (Do this for a month or more, you are the only one capable of knowing how much time is needed for your team to become a little more experienced)
Then, after some time (with them having more experience), you make them post tips and tutorials to others in the same blog. This way they can improve code and writing skills, which are also important in development. (Trying to express yourself to others by writing is a great skill). Doing this in an internal blog is a great step to them if they are a little afraid of creating SO profiles (You avoid the "public forum syndrome", "I'm inexperienced to post there", etc)
If you host your own blog, you can create challenges like creating plugins for the blog itself, trying to use a concept they learned ("create a plugin in wordpress using PHP5 OOP"), or something you think they have to practice.
You can search for open source software that needs help and make them create patches.
...and if you decide to create an open blog, and if it's successfull, we can use it as a great example of tutoring.
(More importantly: make them read a PHP book. Make a deadline to each chapter and exercies proposed in the book. If you can't afford to buy one to them, try free ones.)