I'll respond to the OP 1st and add notes afterward.
While i own/have owned firearms most of my life, i've become an advocate for using a hard-core, bear-grade pepper-spray in my wildlife defense armory. While i've never used pepper-spray against a wild predator (i have used human-grade pepper-spray against large, angry dogs very successfully), i've watched more than a few videos and read fairly bias-free accounts where bear-grade pepper-spray was employed (successfully and not-so-successfully). I am now more convinced than ever before that it is absolutely essential to have a hard-core, bear-grade pepper-spray cannister in my kit.
Something that must be a guiding fact is that an antagonist can cover short distances very quickly - often times faster than most defenders can respond depending on the distance. Also, the attacker has the advantage of choosing when the attack is on - sometimes this is instantly other times when we're looking the other way. While a handgun can be deployed very quickly in the appropriate carry-mode and in the direction of the assault, firing it accurately is another story altogether. Unfortunately, most handgun users do not regularly/adequately train for rapid, accurate deployment of their handgun and even more so altering the direction of fire from that deployment.
Carry-configuration of a firearm is of extreme importance b/c in wildlife vs human confrontation the advantage is usually initially on the side of the attacker (as in almost all situations). We soft-skinned humans can get pretty tore up very quickly and the attacker (linx/cougar/feral canine pack/bear) is usually more OK with some physical pain enroute to their dinner enabling them to continue the fight to our great injury.
A firearm (unless already in-hand) simply will not be
sufficiently accurate nor speedily deployable nor able to deliver adequate immediate stopping force in a quick attack to make it my one and only defense tool. To believe otherwise is a gross over-estimation of ability (of the user or the weapon) or under-estimation of the assailant. I've known LEOs from coast-to-coast (LA County to DC Metro) and a couple of them are truly remarkable marksman who've been in fire-fights. By their own admission, their 'on-street' accuracy was much, much lower even than in stress-induced, heated time-sensitive training/competitions. These are folks who use their side-arm every week and have done so for years. On-street accuracy was much lower than situational. That said, they're all alive and some have been involved in shooting armed assailants.
However, a pissed-off bear or cougar is likely to be on us before we get 2 or 3 rounds in their rear-end. Thats where an overwhelming, all-encompassing pain platform like a hard-core bear-spray can eliminate their ability to continue the attack. It removes their ability to see straight, to breathe and it disrupts their equilibrium. While theres a high risk the user will also get a dose, at least we KNOW what the source is so we can continue spraying - continue the fight.
It's my opinion to construct a multi-tiered defense against assailants. The first tier is avoidance/mitigation of agression. The 2nd is hard-core, bear-grade spray in an 'easy, immediately available' carry-configuration. The 3rd tier - i don't know if i'd be able to employ it given the actual duration/magnitude of the attack - would be a handgun and/or big-ass knife. To me, relying on just one line of defense is lunacy.
Honestly, if i were hiking in bear country i'd be lugging one of these babies!!!
http://www.marlinfirearms.com/Firearms/bigbore/1895SBL.asp
OK maybe not, but the bear-grade spray with my Trailmaster as backup is a minimum!!!