First question:
Well, I've also been asking myself the same question about the slingshot. After using a regular shoulderbag for some years, I changed to a Lowepro Slingshot 200 AW a couple of months back. Much more comfortable to wear when walking around; really easy to swing forward and take the camera out (with an attached lens); but I found changing lenses, filters or lens adapters much easier and faster with the regular shoulderbag. With the slingshot bag, I have a feeling that it's best to take it off before you open the vertical lens compartment. The shoulderbag has the disadvantage that, if you swing your body forward or if you bend to take close-ups, the bag swings and falls forward, which can be really annoying, unless you can find a way to somehow fasten it to your hips with a belt or something...

Second question:
The 475B tripod you're thinking about, weighs 4.3 kilos (add the head, your camera and lens to this). That is really, really heavy to walk around with. If you plan on carrying this by hand, I would definitely think twice about that. Furthermore, the mimimum folded length is 80cm; that is not compact at all if you want to make your path in nature... The 475B is a 'geared' tripod; which means that the center column adjustment can be made very precise by swiveling the gear handle, but usually slower than with a free standing column. About the head: the 804RCR is a 3-way pan and tilt head; heavy-duty (though quite lightweight) and precise; but not as fast as a ball head.
I recently bought a Manfrotto tripod with head myself... when gaining advice from several other 'walking-around' photographers, they advised to get a lighter tripod with a ball head: much easier to carry around and very fast to set up and 'aim'. Based on their recommendations (and my available budget), I had a choice between the 190XPROB and the 055XPROB; the first weighs 1.8kg, the second 2.4kg. They can carry 5 and 7kg respectively, including the head (enough for a DSLR with most telezooms). For the head, I chose a ball head for ease and speed, and believe me, compared to a 3-way head, it's extremely easy and speedy. Turn and swivel it any way you like, up, down, vertical, horizontal, with just one switch... As I finally chose the 190XPROB tripod, I went for the 484RC2 mini ball head (with quick release plate), which matches the tripod perfectly and can still carry 4kg. This combination is just perfect to carry around, very light, easy and fast. The total weight is 2.12kg... compare that to the 5.09kg you're thinking about...

We do not see things as they are. ǝɹɐ ǝʍ sɐ sƃuıɥʇ ǝǝs ǝʍ