[yocto] Questions about 'bitbake core-image-minimal'

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Hi all ,
     Recently,I was learing the yocto project. When I use the cmd "bitbake core-image-minimal" ,the console output the some messages as blow :
    
 Pseudo is not present but is required, building this first before the main build
Parsing recipes...done.
Parsing of 830 .bb files complete (0 cached, 830 parsed). 1106 targets, 34 skipped, 0 masked, 0 errors.
 OE Build Configuration:
BB_VERSION        = "1.15.2"
TARGET_ARCH       = "arm"
TARGET_OS         = "linux-gnueabi"
MACHINE           = "qemuarm"
DISTRO            = "poky"
DISTRO_VERSION    = "1.2.1"
TUNE_FEATURES     = "armv5 dsp thumb arm926ejs"
TARGET_FPU        = "soft"
meta              
meta-yocto        = "<unknown>:<unknown>"
 NOTE: Resolving any missing task queue dependencies
NOTE: Preparing runqueue
NOTE: Executing SetScene Tasks
NOTE: Executing RunQueue Tasks
NOTE: Running task 1 of 63 (ID: 11, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/quilt/quilt-native_0.51.bb, do_fetch)
NOTE: Running task 2 of 63 (ID: 53, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/gnu-config/gnu-config_20111111.bb, do_fetch)
NOTE: Running task 3 of 63 (ID: 60, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/m4/m4-native_1.4.16.bb, do_fetch)
NOTE: Running task 4 of 63 (ID: 32, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/autoconf/autoconf_2.68.bb, do_fetch)
NOTE: package quilt-native-0.51-r1: task do_fetch: Started
NOTE: package m4-native-1.4.16-r2: task do_fetch: Started
NOTE: package gnu-config-native-20111111-r1: task do_fetch: Started
NOTE: package autoconf-native-2.68-r7: task do_fetch: Started
NOTE: package gnu-config-native-20111111-r1: task do_fetch: Succeeded
NOTE: Running task 5 of 63 (ID: 49, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/gnu-config/gnu-config_20111111.bb, do_unpack)
NOTE: package gnu-config-native-20111111-r1: task do_unpack: Started
NOTE: package gnu-config-native-20111111-r1: task do_unpack: Succeeded
NOTE: Running task 6 of 63 (ID: 39, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/automake/automake_1.11.2.bb, do_fetch)
NOTE: package automake-native-1.11.2-r3: task do_fetch: Started
NOTE: package m4-native-1.4.16-r2: task do_fetch: Succeeded
NOTE: Running task 7 of 63 (ID: 56, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/m4/m4-native_1.4.16.bb, do_unpack)
NOTE: package m4-native-1.4.16-r2: task do_unpack: Started
NOTE: package m4-native-1.4.16-r2: task do_unpack: Succeeded
NOTE: Running task 8 of 63 (ID: 46, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/libtool/libtool-native_2.4.2.bb, do_fetch)
NOTE: package libtool-native-2.4.2-r2.0: task do_fetch: Started
NOTE: package autoconf-native-2.68-r7: task do_fetch: Succeeded
NOTE: Running task 9 of 63 (ID: 28, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/autoconf/autoconf_2.68.bb, do_unpack)
NOTE: package automake-native-1.11.2-r3: task do_fetch: Succeeded
NOTE: package autoconf-native-2.68-r7: task do_unpack: Started
NOTE: Running task 10 of 63 (ID: 35, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/automake/automake_1.11.2.bb, do_unpack)
NOTE: package automake-native-1.11.2-r3: task do_unpack: Started
NOTE: package autoconf-native-2.68-r7: task do_unpack: Succeeded
NOTE: Running task 11 of 63 (ID: 25, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/pkgconfig/pkgconfig_0.25.bb, do_fetch)
NOTE: package automake-native-1.11.2-r3: task do_unpack: Succeeded
NOTE: Running task 12 of 63 (ID: 18, virtual:native:/home/ly/yocto/poky-denzil-7.0.1/meta/recipes-support/sqlite/sqlite3_3.7.10.bb, do_fetch)
NOTE: package pkgconfig-native-0.25-r3: task do_fetch: Started
NOTE: package sqlite3-native-3.7.10-r2: task do_fetch: Started
NOTE: package quilt-native-0.51-r1: task do_fetch: Succeeded
NOTE: Running task 13 of 63 (ID: 7, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/quilt/quilt-native_0.51.bb, do_unpack)
NOTE: package quilt-native-0.51-r1: task do_unpack: Started
NOTE: package quilt-native-0.51-r1: task do_unpack: Succeeded
NOTE: Running task 14 of 63 (ID: 8, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/quilt/quilt-native_0.51.bb, do_patch)
NOTE: package quilt-native-0.51-r1: task do_patch: Started
NOTE: package quilt-native-0.51-r1: task do_patch: Succeeded
NOTE: Running task 15 of 63 (ID: 12, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/quilt/quilt-native_0.51.bb, do_configure)
NOTE: package quilt-native-0.51-r1: task do_configure: Started
NOTE: package libtool-native-2.4.2-r2.0: task do_fetch: Succeeded
NOTE: Running task 16 of 63 (ID: 42, /home/ly/yocto/poky-denzil-7.0.1/meta/recipes-devtools/libtool/libtool-native_2.4.2.bb, do_unpack)

     And I am wondering:
 1)I find some package like "automake, autoconf" existing on my host ,can I use "automake" which is already installed on my host rather than to do tasks to install (do_fetch,do_compile) and How  .
2)Why first do_fetch quilt-native ,where the dependency on native devtools things are from.
 
    Thanks ,   
 
      Yu Liu
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