aplay and aplaymidi vs. ALSA??

I am totally mistified now by ALSA. I had it working with 12.0 but now on 13.0 of Slackware I can't get to 1st base.
If I try to use /usr/bin/aplay to play a file I need to use "-t au" to play an au file as it apparently no longer can detect file type (seems this is new). I have my user name in the audio group so that is OK. Yesterday even that didn't help. I kept getting a message about dsm (I think that was it) and about a slave not working. Today now aplay works.
(A) Is it absolutely necessary to reboot for the group file info to be known to the system??

I am trying to play .mid files with aplaymidi. When I use:
aplaymidi -p 0:0 lavieenrose.mid
I get an error:
Cannot connect to port 0:0 - Operation not permitted (even as root)
I am not clear on the 0:0 as to what is which. I tried "-p 0" which is supposed to work.
(B) Since I don't know what is going on with specifying the port can someone inform me?
(C) Any help with why aplaymidi is not working??

cat /proc/asound/cards yields:
0 [V8235 ]: VIA8233 - VIA 8235
VIA 8235 with ALC650F at 0xe000, irq 5
1 [Bt878 ]: Bt87x - Brooktree Bt878
Brooktree Bt878 at 0xdddff000, irq 10
2 [camera ]: USB-Audio - USB camera
USB camera at usb-0000:00:10.3-1.3, full speed

ls -l /proc/asound/*/* yields:
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/Bt878/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/Bt878/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/V8235/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/V8235/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/V8235/via82xx
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/camera/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/camera/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/camera/stream0
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/camera/usbbus
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/camera/usbid
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card0/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card0/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card0/via82xx
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card1/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card1/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card2/id
-rw-r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card2/oss_mixer
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card2/stream0
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card2/usbbus
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/card2/usbid
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/oss/devices
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/oss/sndstat
-r--r--r-- 1 root root 0 2010-11-14 20:50 /proc/asound/seq/clients
(D) Which leads me to ask: why is it an oss_mixer if it is ALSA??

ls -l /dev/snd yields:
crw-rw---- 1 root audio 116, 0 2010-11-14 08:39 controlC0
crw-rw---- 1 root audio 116, 32 2010-11-14 08:39 controlC1
crw-rw---- 1 root audio 116, 64 2010-11-14 08:39 controlC2
crw-rw---- 1 root audio 116, 24 2010-11-14 08:39 pcmC0D0c
crw-rw---- 1 root audio 116, 16 2010-11-14 20:36 pcmC0D0p
crw-rw---- 1 root audio 116, 25 2010-11-14 08:39 pcmC0D1c
crw-rw---- 1 root audio 116, 17 2010-11-14 08:39 pcmC0D1p
crw-rw---- 1 root audio 116, 56 2010-11-14 08:39 pcmC1D0c
crw-rw---- 1 root audio 116, 57 2010-11-14 08:39 pcmC1D1c
crw-rw---- 1 root audio 116, 88 2010-11-14 08:39 pcmC2D0c
crw-rw---- 1 root audio 116, 1 2010-11-14 16:39 seq
crw-rw---- 1 root audio 116, 33 2010-11-14 08:39 timer
Here I see I have a pulse coded modulation with cards 0, 1, and 2. Each has 2 devices 0 & 1 and for each playback and capture capability. But card 2 only has one device (0) which is capture only and NO playback.
(E) Is this because card 2 is a camera and has no playback and only records from it microphone??
(F) What is a sequencer and how is it used with sound?
(G) How is the timer used with sound?

cat /proc/asound/pcm yields:
00-00: VIA 8235 : VIA 8235 : playback 4 : capture 1
00-01: VIA 8235 : VIA 8235 : playback 1 : capture 1
01-00: Bt87x Digital : Bt87x Digital : capture 1
01-01: Bt87x Analog : Bt87x Analog : capture 1
02-00: USB Audio : USB Audio : capture 1

This says (I think) that card 1 & 2 are capture only.
(H) Is card0, device0 using port 4??
(J) How does this match up with the previous list??

cat /proc/asound/seq/* (sequencer info) shows:
Client info
cur clients : 3
peak clients : 4
max clients : 192
Client 0 : "System" [Kernel]
Port 0 : "Timer" (Rwe-)
Port 1 : "Announce" (R-e-)
Connecting To: 15:0
Client 14 : "Midi Through" [Kernel]
Port 0 : "Midi Through Port-0" (RWe-)
Client 15 : "OSS sequencer" [Kernel]
Port 0 : "Receiver" (-we-)
Connected From: 0:1
snd-seq-oss,loaded,0
OSS sequencer emulation version 0.1.8
ALSA client number 15
ALSA receiver port 0
Number of applications: 0
Number of synth devices: 0
(K) Does this mean when using aplaymidi that I should be using -p 0:14 and that x:y is port:client??
(L) I am not clear on port client relationship in this case, HELP??

You can't play midi files on that sound card, so you need to use a softsynth such as timidity++, or get another card.

To get a list of all output ports, you can use the command aconnect -o.