Your primary defenses against cross-contamination include proper planning in the order of what you're cutting and proper cleaning between uses. In the case of your stew, simply cut the vegetables first and then cut your meat. Doing so in this order you won't need to wash the board between the vegetables and meat. If you want to expedite the cooking process, then either use a separate board for the meat first so that you can start browning it while cutting the vegetables, or simply wash and re-use the board. A good scrubbing with hot soapy water is fine for your knife and board (including wood boards).
As mentioned previously, if you're still concerned about bacteria you can rub the board with lemon juice or vinegar which will kill any residual bacteria.
Using separate boards that are relegated to specific meat vs. vegetable duty isn't necessary as long as you're properly cleaning your boards. A board only used for meat items is just as liable to transfer bacteria to the next item being cut on it if it isn't properly washed between uses. That being said, if you're properly cleaning them then it's fine to cut vegetables on a board that's also been used previously for meat.
As for cutting boards, your best bet for the care and maintenance for your knives are either wood or composite materials (usually a laminated product of paper and resin - "Epicurean" being a prominent brand.
Never use a tempered glass cutting board or other hard surface (granite, marble, Corian, etc.) as these are heavily damaging to the edge of your blade and unsafe for you as there is nothing for the knife to bite and grip into and it's much more likely to slip and cut you.
Plastic cutting boards and mats aren't very good on your knives and the boards in particular are either too hard and dull your blade prematurely or are soft and end up with lots of cuts and grooves which then trap food. People often have a false sense of security with plastic boards believing them to be "non-porous". As the board is used, food material ends up crammed into the cuts and grooves and while the boards can go into the dishwasher, that only removes the surface grime, not that which is impacted and over time you increase the potential for bacterial growth to occur.
Wood boards (including bamboo) are much better on your knives but to maintain them in good condition you need to properly maintain them. Periodically, when they look dry (kind of like chapped skin) you need to oil them with mineral oil. The mineral oil you buy at your local drugstore or grocery store pharmacy is fine, no need to buy fancy "block oil" in gourmet shops. Don't use vegetable based oils as they will go rancid and transfer the flavor to your food. I like to give the cutting board a heavy coating at night, let it soak in overnight, and then buff off anything that didn't soak in. This will keep your wood fibers soft and supple so that the board won't split and crack, the fibers will swell back together making it more "self-healing" as you cut on it, and the oil in the wood will repel liquids that would otherwise try to soak in. When a wooden board gets marred and nicked up you just need to take it to the garage and give it a good sanding before dusting off, rinsing and re-oiling.
Don't use bleach on boards (plastic or otherwise) as it will typically leave a distinct smell in the board.
"Better" might be a matter of interpretation. The oils will behave a bit differently, however.
Mineral Oil is a non-drying oil, which means that it will not polymerize (form a plastic-like substance) over time. This is good for oiling cutting boards because it will stay a bit liquid in the wood and flow into cracks and scratches. It is also food-safe and won't go rancid or support microorganisms.
Linseed Oil (AKA Flaxseed Oil, or Flax Oil) is also a good choice, for a different reason. Linseed Oil is a drying oil, which means it will fully polymerize and form a harder plastic layer. This is why it is about the best oil for seasoning cast iron pans. It may be more durable than mineral oil, but lacks the ability to "flow".
A blend of the two sounds like a fine idea. My favorite, Howard's Butcher Block Conditioner is a mix of Mineral Oil and natural waxes like Carnauba and Beeswax, which add a bit of that "durability" that Linseed Oil could add.
What would be a bad choice are most food oils like Canola, Olive Oil, Lard, etc. Unsaturated fats will oxidize (go rancid) and affect your food. Even oils high in saturated fats may have too many anti-oxidants (which are bad in this case), which will prevent polymerization and leave a gummy surface. These semi-drying oils are of no use here.
Whatever you use, make sure it is intended for food (Linseed Oil is a common woodworking finish, and not all versions are intended for use with food). Mineral Oil is probably more convenient for quick daily wipe-downs, while some of the blends are probably a bit more suited toward occasional re-finishing. Either way, regular application and keeping the board dry while not in use will make more difference than the exact type of oil.
Best Answer
The exact number of cutting boards isn't critical, the important piece is minimizing cross contamination. You can use one cutting board safely as long as you're using it in a food-safe order (cut vegetables, then proteins), and follow good sanitation practices (wash & sanitize the board between ingredients). A quick scrub with soap and water and a spritz with a bleach, alcohol, or quat solution between ingredients will minimize your need for different boards.