Mikeact

I Have just purchased this device and as a newbie, (technically dim,) I think it is great but I have question as I must have done something inadvertantly.
'Street View' is shown in the Applications list, but how do I drag it back to the home page , as the Android Shop says that it is installed, but I see it nowhere. Likewise Wikepedia.
And without wishing to go on too long, can I change the tabs that are shown along the bottom when you hit the arrow to show them ?( Task Mgr, Calendar, world Clock,pen Memo, Calculator and Music Player, as I would find other apps more useful to show.
Thanks in advance.